[LLVMgold] Suppress -Wcast-function-type-mismatch diagnostic

llvm/cmake/modules/HandleLLVMOptions.cmake adds -Wextra.
-Wcast-function-type-mismatch was recently added to -Wextra, leading to
a warning for the `get_wrap_symbols` code (https://reviews.llvm.org/D44235).

Suppress the diagnostic.

Pull Request: #89994

llvm/tools/gold/gold-plugin.cpp

@@ -434,8 +434,10 @@ ld_plugin_status onload(ld_plugin_tv *tv) {
       // FIXME: When binutils 2.31 (containing gold 1.16) is the minimum
       // required version, this should be changed to:
       // get_wrap_symbols = tv->tv_u.tv_get_wrap_symbols;
-      get_wrap_symbols =
-          (ld_plugin_get_wrap_symbols)tv->tv_u.tv_message;
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wcast-function-type"
+      get_wrap_symbols = (ld_plugin_get_wrap_symbols)tv->tv_u.tv_message;
+#pragma GCC diagnostic pop
       break;
     default:
       break;