Revert "Build internals of Skia with c++17"

This reverts commit 448ec6f.

Reason for revert: suspect causing 20 test suites failure on LinuxCFI bot.

Sample build: https://ci.chromium.org/p/chromium/builders/ci/Linux%20CFI/15552

20 Test Suite(s) failed.
blink_platform_unittests failed because of:
HarfBuzzShaperTest.PositionForOffsetArabic
ShapeResultBloberizerTest.SubRunWithZeroGlyphs
ShapeResultTest.CopyRangeLatinMultiRunWithHoles
HarfBuzzShaperTest.ResolveCandidateRunsArabicThaiHanLatinTwice
...169 more failure(s) (173 total)...
extensions_browsertests failed because of:
UsbApiTest.InvalidTimeout
PrinterProviderApiTest.GetCapabilitySuccess
URLLoaderFactoryManagerBrowserTest.ContentScriptMatching_CssIsIgnored
WebViewAPITest.TestPartitionChangeAfterNavigation
...168 more failure(s) (172 total)...
vr_pixeltests failed because of:
UiPixelTest.DrawVrBrowsingMode
gfx_unittests failed because of:
Glyphs/GetFallbackFontTest.GetFallbackFont/SDeseretL
...653 more failure(s) (654 total)...
...16 more test(s)...

Sample log: https://logs.chromium.org/logs/chromium/buildbucket/cr-buildbucket.appspot.com/8897418562831814688/+/steps/content_browsertests/0/logs/Deterministic_failure:_AXImageAnnotatorTest.OnImageUpdated__status_CRASH_/0

Original change's description:
> Build internals of Skia with c++17
> 
> Change-Id: I7fedc818b6fad5c08f37c8002268c65eefdf57a2
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1757345
> Commit-Queue: Brian Salomon <bsalomon@google.com>
> Reviewed-by: Mike Klein <mtklein@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#713492}

TBR=bsalomon@google.com,mtklein@chromium.org

Change-Id: I898336f850b4303b8777b1e916a7f251aff4d9c9
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1905042
Reviewed-by: Takashi Sakamoto <tasak@google.com>
Commit-Queue: Takashi Sakamoto <tasak@google.com>
Cr-Commit-Position: refs/heads/master@{#713741}

skia/BUILD.gn

@@ -190,11 +190,7 @@ config("skia_library_config") {
                   # assembly code contains flow control(jmp or jcc) statements.
 
       "/wd4800",  # forcing value to bool 'true/false'(assigning int to bool).
-      "/wd5041",  # out-of-line definition for constexpr static data member is not needed and is deprecated in C++17
     ]
-    cflags_cc = [ "/std:c++17" ]
-  } else {
-    cflags_cc = [ "-std=c++17" ]
   }
 }