[googletest] Suppress -Wdeprecated-declarations in tests

googletest renamed some API functions, but BoringSSL hasn't moved
forward. Rather than fork the BoringSSL code for such a small reason
(TEST_CASE->TEST_SUITE), just disable that warning (in test code only)
for now.

INTK-682 #comment [googletest] Suppress -Wdeprecated-declarations in tests

Test: CQ
Change-Id: I079b6c42123d9a52d1b9c581fa5e31c761c2a23c
diff --git a/BUILD.gn b/BUILD.gn
index 965cc46..18ab020 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -241,6 +241,10 @@
     "src/ssl/test",
   ]
   configs = [ ":internal_config" ]
+
+  # TODO(INTK-682): Newer googletest's are spamming about an API rename, but
+  # BoringSSL hasn't updated yet.
+  cflags = ["-Wno-deprecated-declarations"]
 }
 
 config("fuzz_config") {