Fixed a compiler issue with arm neon build.

Problem: When building webrtc in ARM but not Android:

third_party/webrtc/modules/audio_processing/ns/nsx_core_neon.c: In function 'WebRtcNsx_NoiseEstimationNeon':
third_party/webrtc/modules/audio_processing/ns/nsx_core_neon.c:248:7: note: use -flax-vector-conversions to permit conversions between vectors with differing element types or numbers of subparts

third_party/webrtc/modules/audio_processing/ns/nsx_core_neon.c:248:17: error: incompatible types when assigning to type 'int16x8_t' from type 'uint16x8_t'
Review URL: https://webrtc-codereview.appspot.com/859013

git-svn-id: http://webrtc.googlecode.com/svn/trunk@2917 4adac7df-926f-26a2-2b94-8c16560cd09d

src/build/arm_neon.gypi

@@ -20,16 +20,11 @@
 # }
 
 {
-  'conditions': [
-    ['OS=="android"', {
-      'cflags!': [
-        '-mfpu=vfpv3-d16',
-      ],
-      'cflags': [
-        '-mfpu=neon',
-        '-mfloat-abi=softfp',
-        '-flax-vector-conversions',
-      ],
-    }],
+  'cflags!': [
+    '-mfpu=vfpv3-d16',
+  ],
+  'cflags': [
+    '-mfpu=neon',
+    '-flax-vector-conversions',
   ],
 }