Add assembly.h for use in .S files.

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@85263 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/arm/switch.S b/lib/arm/switch.S
index bfde0da..7b11c4f 100644
--- a/lib/arm/switch.S
+++ b/lib/arm/switch.S
@@ -7,6 +7,8 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "../assembly.h"
+
 //
 // When compiling switch statements in thumb mode, the compiler 
 // can use these __switch* helper functions  The compiler emits a blx to