meson: Disable the intel overlay on non-x86 builds.

It's got calls to rmb/wmb that end up not linking successfully.

Signed-off-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Petri Latvala <petri.latvala@intel.com>
diff --git a/meson.build b/meson.build
index 1cc501f..7a09228 100644
--- a/meson.build
+++ b/meson.build
@@ -121,6 +121,8 @@
 subdir('tools')
 if libdrm_intel.found()
 	subdir('assembler')
-	subdir('overlay')
+	if ['x86', 'x86_64'].contains(host_machine.cpu_family())
+		subdir('overlay')
+	endif
 endif
 subdir('man')