Rename t1_lib.cc to extensions.cc.

This is a bit more self-explanatory, especially now that TLS 1.0 is the
minimum version we implement anyway.

Change-Id: Ic65e9f90bb5cd747328bd9e30b976d1e124c7764
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/48130
Reviewed-by: Adam Langley <agl@google.com>

ssl/CMakeLists.txt

diff --git a/ssl/CMakeLists.txt b/ssl/CMakeLists.txt
index 38c686b..4f4abf8 100644
--- a/ssl/CMakeLists.txt
+++ b/ssl/CMakeLists.txt
@@ -11,6 +11,7 @@
   dtls_method.cc
   dtls_record.cc
   encrypted_client_hello.cc
+  extensions.cc
   handoff.cc
   handshake.cc
   handshake_client.cc
@@ -33,7 +34,6 @@
   ssl_versions.cc
   ssl_x509.cc
   t1_enc.cc
-  t1_lib.cc
   tls_method.cc
   tls_record.cc
   tls13_both.cc

ssl/extensions.cc

diff --git a/ssl/t1_lib.cc b/ssl/extensions.cc
similarity index 100%
rename from ssl/t1_lib.cc
rename to ssl/extensions.cc

ssl/internal.h

diff --git a/ssl/internal.h b/ssl/internal.h
index ac01a61..5b17a95 100644
--- a/ssl/internal.h
+++ b/ssl/internal.h
@@ -1794,7 +1794,7 @@
 
   union {
     // sent is a bitset where the bits correspond to elements of kExtensions
-    // in t1_lib.c. Each bit is set if that extension was sent in a
+    // in extensions.cc. Each bit is set if that extension was sent in a
     // ClientHello. It's not used by servers.
     uint32_t sent = 0;
     // received is a bitset, like |sent|, but is used by servers to record