branch tracer, intel-iommu: fix build with CONFIG_BRANCH_TRACER=y

Fix the branch tracer barfing on comma statements within if ()
statements.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index 8872ad6..37bcb50 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -115,7 +115,9 @@
  * "Define 'is'", Bill Clinton
  * "Define 'if'", Steven Rostedt
  */
-#define if(cond) if (__builtin_constant_p((cond)) ? !!(cond) :		\
+#define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) )
+#define __trace_if(cond) \
+	if (__builtin_constant_p((cond)) ? !!(cond) :			\
 	({								\
 		int ______r;						\
 		static struct ftrace_branch_data			\