THRIFT-3288 c_glib: Build unit tests without compiler warnings

These changes allow the unit tests for C (GLib) to build without
compiler warnings, even with additional warnings enabled. They
include

- Disabling string-function optimizations when glibc is used, as
  these produce compiler warnings when a string function is used
  within a call to assert ();

- Remove the "LL" suffix (added in C99) from 64-bit integer
  literals;

- Replace C++-style ("//") comments with C-style equivalents;

- Remove unused constant declarations that generated warnings;
  and

- Mark (or remove, from main ()) unused function parameters.
diff --git a/lib/c_glib/test/testsimpleserver.c b/lib/c_glib/test/testsimpleserver.c
index cb270b4..3af2eeb 100755
--- a/lib/c_glib/test/testsimpleserver.c
+++ b/lib/c_glib/test/testsimpleserver.c
@@ -53,6 +53,11 @@
 test_processor_process (ThriftProcessor *processor, ThriftProtocol *in,
                         ThriftProtocol *out, GError **error)
 {
+  THRIFT_UNUSED_VAR (processor);
+  THRIFT_UNUSED_VAR (in);
+  THRIFT_UNUSED_VAR (out);
+  THRIFT_UNUSED_VAR (error);
+
   return FALSE;
 }