Win/GN: Make no_exception config explicit.

build/config/gcc/BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/compiler/compiler.gni")
 import("//build/config/sanitizers/sanitizers.gni")
 import("//build/config/sysroot.gni")
 import("//build/toolchain/toolchain.gni")
 
 # This config causes functions not to be automatically exported from shared
@@ skipping 99 matching lines @@
 
       # TODO(GYP): Do we need a check on the binutils version here?
       #
       # Newer binutils don't set DT_RPATH unless you disable "new" dtags
       # and the new DT_RUNPATH doesn't work without --no-as-needed flag.
       "-Wl,--disable-new-dtags",
     ]
   }
 }
 
+# TODO(jmadill): Remove this when ANGLE and libc++ don't depend on it.

[brettw, 2016/08/31 17:01:20]

I don't see how leaving this here helps ANGLE. It excepts to be able to remove
this from the list of default configs (removing something that isn't there is an
error), but you already removed it. Keeping this config here unreferenced
doesn't help those cases.

I don't know how much ANGLE needs this specific thing. If they can tolerate this
being wrong for a day, we should keep the reference in the default configs to
this one, but make this one empty. This way the GN angle code will run but it
will temporarily have no exceptions until it's updated to the shared one.

If that's not possible, we may need a 3-way patch. For a tricky case in the
past, I make a new .gni file in build somewhere with a bool set to false,
updated the other repo to key it's behavior off of the bool,  waited for a roll,
then update the behavior and flipped the bool, then removed everything.

 config("no_exceptions") {
   cflags_cc = [ "-fno-exceptions" ]
   cflags_objcc = cflags_cc
 }