x86inc: fix compilation with NASM

Change-Id: I5978921ab1ccad6648a5bde6ad023c3e3430f5f4
diff --git a/third_party/x86inc/x86inc.asm b/third_party/x86inc/x86inc.asm
index 2134676..99453a9 100644
--- a/third_party/x86inc/x86inc.asm
+++ b/third_party/x86inc/x86inc.asm
@@ -234,10 +234,10 @@
         %define r%1mp %2
     %elif ARCH_X86_64 ; memory
         %define r%1m [rsp + stack_offset + %6]
-        %define r%1mp qword r %+ %1m
+        %define r%1mp qword r %+ %1 %+ m
     %else
         %define r%1m [esp + stack_offset + %6]
-        %define r%1mp dword r %+ %1m
+        %define r%1mp dword r %+ %1 %+ m
     %endif
     %define r%1  %2
 %endmacro