Add malloc test support to unit tests.

Currently far from passing and I haven't even tried with a leak checker yet.
Also bn_test is slow.

Change-Id: I4fe2783aa5f7897839ca846062ae7e4a367d2469
Reviewed-on: https://boringssl-review.googlesource.com/4794
Reviewed-by: Adam Langley <agl@google.com>

ssl/CMakeLists.txt

diff --git a/ssl/CMakeLists.txt b/ssl/CMakeLists.txt
index f016046..cf5a29d 100644
--- a/ssl/CMakeLists.txt
+++ b/ssl/CMakeLists.txt
@@ -40,6 +40,8 @@
   ssl_test
 
   ssl_test.cc
+
+  $<TARGET_OBJECTS:test_support>
 )
 
 target_link_libraries(ssl_test ssl crypto)