Move libssl's internals into the bssl namespace.

This is horrible, but everything else I tried was worse. The goal with
this CL is to take the extern "C" out of ssl/internal.h and move most
symbols to namespace bssl, so we can start using C++ helpers and
destructors without worry.

Complications:

- Public API functions must be extern "C" and match their declaration in
  ssl.h, which is unnamespaced. C++ really does not want you to
  interleave namespaced and unnamespaced things. One can actually write
  a namespaced extern "C" function, but this means, from C++'s
  perspective, the function is namespaced. Trying to namespace the
  public header would worked but ended up too deep a rabbithole.

- Our STACK_OF macros do not work right in namespaces.

- The typedefs for our exposed but opaque types are visible in the
  header files and copied into consuming projects as forward
  declarations. We ultimately want to give SSL a destructor, but
  clobbering an unnamespaced ssl_st::~ssl_st seems bad manners.

- MSVC complains about ambiguous names if one typedefs SSL to bssl::SSL.

This CL opts for:

- ssl/*.cc must begin with #define BORINGSSL_INTERNAL_CXX_TYPES. This
  informs the public headers to create forward declarations which are
  compatible with our namespaces.

- For now, C++-defined type FOO ends up at bssl::FOO with a typedef
  outside. Later I imagine we'll rename many of them.

- Internal functions get namespace bssl, so we stop worrying about
  stomping the tls1_prf symbol. Exported C functions are stuck as they
  are. Rather than try anything weird, bite the bullet and reorder files
  which have a mix of public and private functions. I expect that over
  time, the public functions will become fairly small as we move logic
  to more idiomatic C++.

  Files without any public C functions can just be written normally.

- To avoid MSVC troubles, some bssl types are renamed to CPlusPlusStyle
  in advance of them being made idiomatic C++.

Bug: 132
Change-Id: Ic931895e117c38b14ff8d6e5a273e868796c7581
Reviewed-on: https://boringssl-review.googlesource.com/18124
Reviewed-by: David Benjamin <davidben@google.com>
diff --git a/ssl/t1_enc.cc b/ssl/t1_enc.cc
index c224240..1efd834 100644
--- a/ssl/t1_enc.cc
+++ b/ssl/t1_enc.cc
@@ -133,6 +133,8 @@
  * OTHER ENTITY BASED ON INFRINGEMENT OF INTELLECTUAL PROPERTY RIGHTS OR
  * OTHERWISE. */
 
+#define BORINGSSL_INTERNAL_CXX_TYPES
+
 #include <openssl/ssl.h>
 
 #include <assert.h>
@@ -150,6 +152,8 @@
 #include "internal.h"
 
 
+namespace bssl {
+
 /* tls1_P_hash computes the TLS P_<hash> function as described in RFC 5246,
  * section 5. It XORs |out_len| bytes to |out|, using |md| as the hash and
  * |secret| as the secret. |seed1| through |seed3| are concatenated to form the
@@ -442,34 +446,6 @@
   return ssl->method->set_write_state(ssl, aead_ctx);
 }
 
-size_t SSL_get_key_block_len(const SSL *ssl) {
-  return 2 * ((size_t)ssl->s3->tmp.new_mac_secret_len +
-              (size_t)ssl->s3->tmp.new_key_len +
-              (size_t)ssl->s3->tmp.new_fixed_iv_len);
-}
-
-int SSL_generate_key_block(const SSL *ssl, uint8_t *out, size_t out_len) {
-  if (ssl3_protocol_version(ssl) == SSL3_VERSION) {
-    return ssl3_prf(out, out_len, SSL_get_session(ssl)->master_key,
-                    SSL_get_session(ssl)->master_key_length,
-                    TLS_MD_KEY_EXPANSION_CONST, TLS_MD_KEY_EXPANSION_CONST_SIZE,
-                    ssl->s3->server_random, SSL3_RANDOM_SIZE,
-                    ssl->s3->client_random, SSL3_RANDOM_SIZE);
-  }
-
-  const EVP_MD *digest = ssl_get_handshake_digest(
-      SSL_get_session(ssl)->cipher->algorithm_prf, ssl3_protocol_version(ssl));
-  if (digest == NULL) {
-    OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
-    return 0;
-  }
-  return tls1_prf(digest, out, out_len, SSL_get_session(ssl)->master_key,
-                  SSL_get_session(ssl)->master_key_length,
-                  TLS_MD_KEY_EXPANSION_CONST, TLS_MD_KEY_EXPANSION_CONST_SIZE,
-                  ssl->s3->server_random, SSL3_RANDOM_SIZE,
-                  ssl->s3->client_random, SSL3_RANDOM_SIZE);
-}
-
 int tls1_generate_master_secret(SSL_HANDSHAKE *hs, uint8_t *out,
                                 const uint8_t *premaster,
                                 size_t premaster_len) {
@@ -507,6 +483,38 @@
   return SSL3_MASTER_SECRET_SIZE;
 }
 
+}  // namespace bssl
+
+using namespace bssl;
+
+size_t SSL_get_key_block_len(const SSL *ssl) {
+  return 2 * ((size_t)ssl->s3->tmp.new_mac_secret_len +
+              (size_t)ssl->s3->tmp.new_key_len +
+              (size_t)ssl->s3->tmp.new_fixed_iv_len);
+}
+
+int SSL_generate_key_block(const SSL *ssl, uint8_t *out, size_t out_len) {
+  if (ssl3_protocol_version(ssl) == SSL3_VERSION) {
+    return ssl3_prf(out, out_len, SSL_get_session(ssl)->master_key,
+                    SSL_get_session(ssl)->master_key_length,
+                    TLS_MD_KEY_EXPANSION_CONST, TLS_MD_KEY_EXPANSION_CONST_SIZE,
+                    ssl->s3->server_random, SSL3_RANDOM_SIZE,
+                    ssl->s3->client_random, SSL3_RANDOM_SIZE);
+  }
+
+  const EVP_MD *digest = ssl_get_handshake_digest(
+      SSL_get_session(ssl)->cipher->algorithm_prf, ssl3_protocol_version(ssl));
+  if (digest == NULL) {
+    OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
+    return 0;
+  }
+  return tls1_prf(digest, out, out_len, SSL_get_session(ssl)->master_key,
+                  SSL_get_session(ssl)->master_key_length,
+                  TLS_MD_KEY_EXPANSION_CONST, TLS_MD_KEY_EXPANSION_CONST_SIZE,
+                  ssl->s3->server_random, SSL3_RANDOM_SIZE,
+                  ssl->s3->client_random, SSL3_RANDOM_SIZE);
+}
+
 int SSL_export_keying_material(SSL *ssl, uint8_t *out, size_t out_len,
                                const char *label, size_t label_len,
                                const uint8_t *context, size_t context_len,