Add a [rtc_]build_with_neon variable to unify conditions.

webrtc/BUILD.gn

 # Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
 #
 # Use of this source code is governed by a BSD-style license
 # that can be found in the LICENSE file in the root of the source
 # tree. An additional intellectual property rights grant can be found
 # in the file PATENTS.  All contributing project authors may
 # be found in the AUTHORS file in the root of the source tree.
 
 # TODO(kjellander): Rebase this to webrtc/build/common.gypi changes after r6330.
 
@@ skipping 146 matching lines @@
     # functions. Ensure they are disabled for all compilers.
     cflags += [
       "-fno-builtin-cos",
       "-fno-builtin-sin",
       "-fno-builtin-cosf",
       "-fno-builtin-sinf",
     ]
   }
 }
 
+# Add to ARM NEON targets.
+config("arm_neon_config") {

[Andrew MacDonald, 2015/06/17 17:44:16]

kjellander: I'm not super familiar with this stuff. Do you see any reason this
won't work?

+  if (current_cpu == "arm") {
+    # Enable compilation for the ARM v7 Neon instruction set. This is needed
+    # since //build/config/arm.gni only enables Neon for iOS, not Android.
+    # This provides the same functionality as webrtc/build/arm_neon.gypi.
+    configs -= [ "//build/config/compiler:compiler_arm_fpu" ]
+    cflags = [ "-mfpu=neon" ]
+  }
+
+  # Disable LTO due to compiler bug.
+  if (rtc_use_lto) {
+    cflags -= [
+      "-flto",
+      "-ffat-lto-objects",
+    ]
+  }
+}
+
 source_set("webrtc") {
   sources = [
     "call.h",
     "config.h",
     "experiments.h",
     "frame_callback.h",
     "transport.h",
   ]
 
   configs += [ ":common_config" ]
@@ skipping 54 matching lines @@
 
   configs += [ ":common_config" ]
   public_configs = [ ":common_inherited_config" ]
 }
 
 source_set("gtest_prod") {
   sources = [
     "test/testsupport/gtest_prod_util.h",
   ]
 }