meson: Enable VC4's NEON assembly support.

Reviewed-by: Dylan Baker <dylan@pnwbakers.com>
Reviewed-by: Eric Engestrom <eric.engestrom@imgtec.com>
Tested-by: Timothy Arceri <tarceri@itsqueeze.com>

meson.build

@@ -489,8 +489,8 @@ endif
 
 # FIXME: enable asm when cross compiler
 # This is doable (autotools does it), but it's not of immediate concern
-if meson.is_cross_build()
-  message('Cross compiling, disabling asm')
+if meson.is_cross_build() and host_machine.cpu_family().startswith('x86')
+  message('Cross compiling, disabling x86/x86_64 asm')
   with_asm = false
 endif