libvpx: exclude NEON target on x86 for GN build

Exclude NEON targets such that GN can build for all targets.

TBR=tomfinegan

Review URL: https://codereview.chromium.org/550533002

git-svn-id: http://src.chromium.org/svn/trunk/deps/third_party/libvpx@291837 4ff67af0-8c30-449e-8e8b-ad334ec8d88c
diff --git a/BUILD.gn b/BUILD.gn
index 86036ce..2e35ef9 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -170,10 +170,12 @@
   }
 }
 
-static_library("libvpx_intrinsics_neon") {
-  configs += [ ":libvpx_config" ]
-  cflags = [ "-mfpu=neon", "-mfloat-abi=softfp" ]
-  sources = libvpx_srcs_arm_neon_cpu_detect_neon
+if (cpu_arch_full == "arm-neon-cpu-detect") {
+  static_library("libvpx_intrinsics_neon") {
+    configs += [ ":libvpx_config" ]
+    cflags = [ "-mfpu=neon", "-mfloat-abi=softfp" ]
+    sources = libvpx_srcs_arm_neon_cpu_detect_neon
+  }
 }
 
 static_library("libvpx") {