Add a [rtc_]build_with_neon variable to unify conditions.

webrtc/modules/audio_processing/audio_processing.gypi

Index: webrtc/modules/audio_processing/audio_processing.gypi
diff --git a/webrtc/modules/audio_processing/audio_processing.gypi b/webrtc/modules/audio_processing/audio_processing.gypi
index a4f9b39a93fdd44a09c0d30f6534566722a68f3e..f0d56691c04a53389c493a7c82c5d62424b89f30 100644
--- a/webrtc/modules/audio_processing/audio_processing.gypi
+++ b/webrtc/modules/audio_processing/audio_processing.gypi
@@ -186,7 +186,7 @@
         ['target_arch=="ia32" or target_arch=="x64"', {
           'dependencies': ['audio_processing_sse2',],
         }],
-        ['(target_arch=="arm" and arm_version>=7) or target_arch=="arm64"', {
+        ['build_with_neon==1', {
           'dependencies': ['audio_processing_neon',],
         }],
         ['target_arch=="mipsel" and mips_arch_variant!="r6"', {
@@ -249,7 +249,7 @@
         },
       ],
     }],
-    ['(target_arch=="arm" and arm_version>=7) or target_arch=="arm64"', {
+    ['build_with_neon==1', {
       'targets': [{
         'target_name': 'audio_processing_neon',
         'type': 'static_library',
@@ -263,15 +263,6 @@
           'aecm/aecm_core_neon.c',
           'ns/nsx_core_neon.c',
         ],
-        'conditions': [
-          # Disable LTO in audio_processing_neon target due to compiler bug
-          ['use_lto==1', {
-            'cflags!': [
-              '-flto',
-              '-ffat-lto-objects',
-            ],
-          }],
-        ],
       }],
     }],
   ],