Firefox (75) and AOM itself fail to build with NEON enabled. As such
we should disable it for now.

In file included from /home/buildozer/aports/community/firefox/src/firefox-75.0/third_party/aom/aom_dsp/arm/blend_a64_mask_neon.c:12:
/home/buildozer/aports/community/firefox/src/firefox-75.0/third_party/aom/av1/common/arm/mem_neon.h: In function 'load_u8_8x8':
/usr/lib/gcc/armv7-alpine-linux-musleabihf/9.3.0/include/arm_neon.h:10303:1: error: inlining failed in call to always_inline 'vld1_u8': target specific option mismatch
10303 | vld1_u8 (const uint8_t * __a)
      | ^~~~~~~
--- a/media/libaom/moz.build	2020-04-09 08:20:14.608439591 +0200
+++ b/media/libaom/moz.build	2020-04-09 08:20:21.801745246 +0200
@@ -42,26 +42,6 @@
         ASFLAGS += [ '-I%s/media/libaom/config/linux/ia32/' % TOPSRCDIR ]
         LOCAL_INCLUDES += [ '/media/libaom/config/linux/ia32/' ]
         EXPORTS.aom += [ 'config/linux/ia32/config/aom_config.h' ]
-elif CONFIG['CPU_ARCH'] == 'arm':
-    EXPORTS.aom += files['ARM_EXPORTS']
-    ASFLAGS += [
-        '-I%s/media/libaom/config/linux/arm/' % TOPSRCDIR,
-        '-I%s/libaom' % OBJDIR,
-    ]
-    LOCAL_INCLUDES += [ '/media/libaom/config/linux/arm/' ]
-    EXPORTS.aom += [ 'config/linux/arm/config/aom_config.h' ]
-
-    SOURCES += files['ARM_SOURCES']
-
-    for f in SOURCES:
-        if f.endswith('neon.c'):
-            SOURCES[f].flags += CONFIG['VPX_ASFLAGS']
-
-    if CONFIG['OS_TARGET'] == 'Android':
-        # For cpu-features.h
-        LOCAL_INCLUDES += [
-            '%%%s/sources/android/cpufeatures' % CONFIG['ANDROID_NDK'],
-        ]
 else:
     # Generic C-only configuration
     EXPORTS.aom += files['GENERIC_EXPORTS']