Rename s3_{clnt,srvr}.c

Give them much more reasonable names.

Change-Id: Id14d983ab3231da21a4f987e662c2e01af7a2cd6
Reviewed-on: https://boringssl-review.googlesource.com/8185
Reviewed-by: Steven Valdez <svaldez@google.com>
Reviewed-by: David Benjamin <davidben@google.com>

ssl/CMakeLists.txt

@@ -6,6 +6,8 @@ add_library(
   ssl
 
   custom_extensions.c
+  handshake_server.c
+  handshake_client.c
   d1_both.c
   d1_lib.c
   d1_meth.c
@@ -13,12 +15,10 @@ add_library(
   d1_srtp.c
   dtls_record.c
   s3_both.c
-  s3_clnt.c
   s3_enc.c
   s3_lib.c
   s3_meth.c
   s3_pkt.c
-  s3_srvr.c
   ssl_aead_ctx.c
   ssl_asn1.c
   ssl_buffer.c