Add SSL_CIPHER_is_DHE.

Change-Id: I158d1fa1a6b70a278054862326562988c97911b5
Reviewed-on: https://boringssl-review.googlesource.com/8140
Reviewed-by: David Benjamin <davidben@google.com>
diff --git a/ssl/ssl_cipher.c b/ssl/ssl_cipher.c
index 74645ed..e78374b 100644
--- a/ssl/ssl_cipher.c
+++ b/ssl/ssl_cipher.c
@@ -1691,6 +1691,10 @@
   return (cipher->algorithm_auth & SSL_aECDSA) != 0;
 }
 
+int SSL_CIPHER_is_DHE(const SSL_CIPHER *cipher) {
+  return (cipher->algorithm_mkey & SSL_kDHE) != 0;
+}
+
 int SSL_CIPHER_is_ECDHE(const SSL_CIPHER *cipher) {
   return (cipher->algorithm_mkey & SSL_kECDHE) != 0;
 }