Bug 1692940 - Switch aom build to nasm instead of yasm. r=firefox-build-system-reviewers,jbauman,dmajor,andi

nasm doesn't like compiling x86_abi_support.asm
(https://bugzilla.nasm.us/show_bug.cgi?id=3392738), which is actually an
include file, rather than a source file, so it shouldn't have been in
the list of sources in the first place (libvpx has a similar file that
is excluded already, for instance).

I was considering updating the vendoring script, but it turns out it
doesn't produce the current contents in-tree (which even breaks the
build), and aom is set to be removed (bug 1635296)...

Differential Revision: https://phabricator.services.mozilla.com/D105430

media/libaom/moz.build

@@ -13,7 +13,7 @@ include('sources.mozbuild')
 if CONFIG['CPU_ARCH'] == 'x86_64':
     EXPORTS.aom += files['X64_EXPORTS']
     SOURCES += files['X64_SOURCES']
-    USE_YASM = True
+    USE_NASM = True
     if CONFIG['OS_TARGET'] == 'WINNT':
         ASFLAGS += [ '-I%s/media/libaom/config/win/x64/' % TOPSRCDIR ]
         LOCAL_INCLUDES += [ '/media/libaom/config/win/x64/' ]
@@ -32,7 +32,7 @@ if CONFIG['CPU_ARCH'] == 'x86_64':
 elif CONFIG['CPU_ARCH'] == 'x86':
     EXPORTS.aom += files['IA32_EXPORTS']
     SOURCES += files['IA32_SOURCES']
-    USE_YASM = True
+    USE_NASM = True
     if CONFIG['OS_TARGET'] == 'WINNT':
         ASFLAGS += [ '-I%s/media/libaom/config/win/ia32/' % TOPSRCDIR ]
         LOCAL_INCLUDES += [ '/media/libaom/config/win/ia32/' ]

media/libaom/sources.mozbuild

@@ -276,7 +276,6 @@ files = {
     '../../third_party/aom/aom_dsp/x86/loopfilter_sse2.c',
     '../../third_party/aom/aom_mem/aom_mem.c',
     '../../third_party/aom/aom_ports/emms.asm',
-    '../../third_party/aom/aom_ports/x86_abi_support.asm',
     '../../third_party/aom/aom_scale/aom_scale_rtcd.c',
     '../../third_party/aom/aom_scale/generic/aom_scale.c',
     '../../third_party/aom/aom_scale/generic/gen_scalers.c',