Use C99 for size_t loops.

This was done just by grepping for 'size_t i;' and 'size_t j;'. I left
everything in crypto/x509 and friends alone.

There's some instances in gcm.c that are non-trivial and pulled into a
separate CL for ease of review.

Change-Id: I6515804e3097f7e90855f1e7610868ee87117223
Reviewed-on: https://boringssl-review.googlesource.com/10801
Reviewed-by: Adam Langley <agl@google.com>
Commit-Queue: Adam Langley <agl@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>
diff --git a/ssl/ssl_lib.c b/ssl/ssl_lib.c
index bdc1074..04a1411 100644
--- a/ssl/ssl_lib.c
+++ b/ssl/ssl_lib.c
@@ -2533,13 +2533,12 @@
 static int cbb_add_hex(CBB *cbb, const uint8_t *in, size_t in_len) {
   static const char hextable[] = "0123456789abcdef";
   uint8_t *out;
-  size_t i;
 
   if (!CBB_add_space(cbb, &out, in_len * 2)) {
     return 0;
   }
 
-  for (i = 0; i < in_len; i++) {
+  for (size_t i = 0; i < in_len; i++) {
     *(out++) = (uint8_t)hextable[in[i] >> 4];
     *(out++) = (uint8_t)hextable[in[i] & 0xf];
   }
@@ -2708,9 +2707,8 @@
    * as a min/max range by picking the lowest contiguous non-empty range of
    * enabled protocols. Note that this means it is impossible to set a maximum
    * version of the higest supported TLS version in a future-proof way. */
-  size_t i;
   int any_enabled = 0;
-  for (i = 0; i < kVersionsLen; i++) {
+  for (size_t i = 0; i < kVersionsLen; i++) {
     /* Only look at the versions already enabled. */
     if (min_version > kVersions[i].version) {
       continue;