src: remove ignore GCC -Wcast-function-type for v8

This reverts Commit 3ff2aec ("src:
ignore GCC -Wcast-function-type for v8.h") and Commit
2462a2c ("src: fix ignore GCC
-Wcast-function-type for older compilers") as this has
now been included in the V8 version being used.

Refs:
v8/v8@f08cbfd

Author: danbev

src/base_object-inl.h

@@ -28,14 +28,7 @@
 #include "env-inl.h"
 #include "util.h"
 
-#if (__GNUC__ >= 8) && !defined(__clang__)
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wcast-function-type"
-#endif
 #include "v8.h"
-#if (__GNUC__ >= 8) && !defined(__clang__)
-#pragma GCC diagnostic pop
-#endif
 
 namespace node {
 

src/node.h

@@ -60,14 +60,7 @@
 # define SIGKILL 9
 #endif
 
-#if (__GNUC__ >= 8) && !defined(__clang__)
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wcast-function-type"
-#endif
 #include "v8.h"  // NOLINT(build/include_order)
-#if (__GNUC__ >= 8) && !defined(__clang__)
-#pragma GCC diagnostic pop
-#endif
 
 #include "v8-platform.h"  // NOLINT(build/include_order)
 #include "node_version.h"  // NODE_MODULE_VERSION

src/util.h

@@ -24,14 +24,7 @@
 
 #if defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS
 
-#if (__GNUC__ >= 8) && !defined(__clang__)
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wcast-function-type"
-#endif
 #include "v8.h"
-#if (__GNUC__ >= 8) && !defined(__clang__)
-#pragma GCC diagnostic pop
-#endif
 
 #include <climits>
 #include <cstddef>