Add stubs for abseil flags.

This CL also removes support for using the gflags library to modify the
flags.

PiperOrigin-RevId: 361583626

snappy-test.h

@@ -56,27 +56,8 @@
 #include <windows.h>
 #endif
 
-#ifdef HAVE_GFLAGS
-
-#include <gflags/gflags.h>
-
-// This is tricky; both gflags and Google Test want to look at the command line
-// arguments. Google Test seems to be the most happy with unknown arguments,
-// though, so we call it first and hope for the best.
-#define InitGoogle(argv0, argc, argv, remove_flags) \
-  google::ParseCommandLineFlags(argc, argv, remove_flags);
-
-#else
-
-// If we don't have the gflags package installed, these can only be
-// changed at compile time.
-#define DEFINE_int32(flag_name, default_value, description) \
-  static int FLAGS_ ## flag_name = default_value;
-
 #define InitGoogle(argv0, argc, argv, remove_flags) ((void)(0))
 
-#endif
-
 #ifdef HAVE_LIBZ
 #include "zlib.h"
 #endif