Revert "GN: detect is_clang, use it to switch Clang to warning blacklist."

This reverts commit I09c3487adfeb26a6fb07e1939cb927c5d7de3107.

Reason for revert: -Wover-aligned on x86 Android bots

Original issue's description:
> GN: detect is_clang, use it to switch Clang to warning blacklist.
> 
> BUG=skia:
> 
> GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2599
> 
> Change-Id: I09c3487adfeb26a6fb07e1939cb927c5d7de3107
> Reviewed-on: https://skia-review.googlesource.com/2599
> Reviewed-by: Ben Wagner <bungeman@google.com>
> Commit-Queue: Mike Klein <mtklein@chromium.org>
> 

TBR=mtklein@chromium.org,bungeman@google.com,reviews@skia.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Change-Id: Ic07bf7896a305be6c377f14a573cb10836f1a6f8
Reviewed-on: https://skia-review.googlesource.com/2601
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>

2 files changed, 0 insertions, 91 deletions

diff --git a/gn/BUILD.gn b/gn/BUILD.gn
index 551d429639..427ab2eec6 100644
--- a/gn/BUILD.gn
+++ b/gn/BUILD.gn
@@ -24,13 +24,6 @@ declare_args() {
   cc_wrapper = ""
 }
 
-is_clang = exec_script("is_clang.py",
-                       [
-                         cc,
-                         cxx,
-                       ],
-                       "value")
-
 config("default") {
   asmflags = []
   cflags = []
@@ -77,73 +70,6 @@ config("default") {
 
       "-Wnon-virtual-dtor",
     ]
-    if (is_clang) {
-      cflags += [
-        "-Weverything",
-        "-Wno-unknown-warning-option",  # Let older Clangs ignore newer Clangs' warnings.
-      ]
-
-      # High priority to fix!
-      cflags += [
-        "-Wno-comma",
-        "-Wno-conditional-uninitialized",
-        "-Wno-covered-switch-default",
-        "-Wno-deprecated",
-        "-Wno-format-nonliteral",
-        "-Wno-shadow",
-        "-Wno-shift-sign-overflow",
-        "-Wno-undefined-func-template",
-        "-Wno-undefined-reinterpret-cast",
-      ]
-
-      cflags += [
-        "-Wno-cast-align",
-        "-Wno-class-varargs",
-        "-Wno-conversion",
-        "-Wno-disabled-macro-expansion",
-        "-Wno-documentation",
-        "-Wno-documentation-unknown-command",
-        "-Wno-double-promotion",
-        "-Wno-exit-time-destructors",  # TODO: OK outside libskia
-        "-Wno-extra-semi",
-        "-Wno-float-conversion",
-        "-Wno-float-equal",
-        "-Wno-global-constructors",  # TODO: OK outside libskia
-        "-Wno-gnu-anonymous-struct",
-        "-Wno-gnu-zero-variadic-macro-arguments",
-        "-Wno-missing-prototypes",
-        "-Wno-missing-variable-declarations",
-        "-Wno-nested-anon-types",
-        "-Wno-newline-eof",
-        "-Wno-pedantic",
-        "-Wno-reserved-id-macro",
-        "-Wno-sign-conversion",
-        "-Wno-switch-enum",
-        "-Wno-undef",
-        "-Wno-unreachable-code",
-        "-Wno-unreachable-code-break",
-        "-Wno-unreachable-code-return",
-        "-Wno-unused-macros",
-        "-Wno-unused-member-function",
-      ]
-      cflags_cc += [
-        "-Wno-abstract-vbase-init",
-        "-Wno-range-loop-analysis",
-        "-Wno-weak-vtables",
-      ]
-
-      # We are unlikely to want to fix these.
-      cflags += [
-        "-Wno-implicit-fallthrough",
-        "-Wno-missing-noreturn",
-        "-Wno-old-style-cast",
-        "-Wno-padded",
-      ]
-      cflags_cc += [
-        "-Wno-c++98-compat",
-        "-Wno-c++98-compat-pedantic",
-      ]
-    }
   }
 
   if (current_cpu == "arm") {
diff --git a/gn/is_clang.py b/gn/is_clang.py
deleted file mode 100755
index 99173a004c..0000000000
--- a/gn/is_clang.py
+++ /dev/null
@@ -1,17 +0,0 @@
-#!/usr/bin/env python
-#
-# Copyright 2016 Google Inc.
-#
-# Use of this source code is governed by a BSD-style license that can be
-# found in the LICENSE file.
-
-import subprocess
-import sys
-cc,cxx = sys.argv[1:3]
-
-if ('clang' in subprocess.check_output([cc,  '--version']) and
-    'clang' in subprocess.check_output([cxx, '--version'])):
-  print 'true'
-else:
-  print 'false'
-