Add a [rtc_]build_with_neon variable to unify conditions.

webrtc/BUILD.gn

Index: webrtc/BUILD.gn
diff --git a/webrtc/BUILD.gn b/webrtc/BUILD.gn
index 6c6c23cfa0550cc00fbe5fac426d1f6ebece599d..483f8089510bbf94f5ada7263dba9f3e258c4a14 100644
--- a/webrtc/BUILD.gn
+++ b/webrtc/BUILD.gn
@@ -164,6 +164,25 @@ config("common_config") {
   }
 }
 
+# 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",