Revert "[android] Override __cxa_demangle() in PRODUCT mode"

This reverts commit 9fce277b7e.

I verfied locally that this change no longer reduces binary size with a custom-built libcxxabi/libcxx and LTO.

Change-Id: I05dfb83597c064ba976573da5547ae79c0d41d1c
Reviewed-on: https://dart-review.googlesource.com/c/84831
Reviewed-by: Zach Anderson <zra@google.com>
Commit-Queue: Zach Anderson <zra@google.com>

runtime/vm/native_symbol_android.cc

@@ -10,21 +10,6 @@
 #include <cxxabi.h>  // NOLINT
 #include <dlfcn.h>   // NOLINT
 
-// Even though it's not used in a PRODUCT build, __cxa_demangle() still ends up
-// in the resulting binary for Android. Blowing it away by redefining it like
-// so saves >90KB of binary size.
-#if defined(PRODUCT)
-extern "C" char* __cxa_demangle(const char* mangled_name,
-                                char* buf,
-                                size_t* n,
-                                int* status) {
-  if (status) {
-    *status = -1;
-  }
-  return NULL;
-}
-#endif
-
 namespace dart {
 
 void NativeSymbolResolver::Init() {}