Add RSB instruction to the ARM integrated assembler.

src/IceAssemblerARM32.h

Index: src/IceAssemblerARM32.h
diff --git a/src/IceAssemblerARM32.h b/src/IceAssemblerARM32.h
index c45fc70557b6df82858cc9a5289107583f1473f5..37ea4416fde43ff8fca9a7bc859e4d6c7ace8d72 100644
--- a/src/IceAssemblerARM32.h
+++ b/src/IceAssemblerARM32.h
@@ -249,6 +249,9 @@ public:
   // Note: Registers is a bitset, where bit n corresponds to register Rn.
   void pushList(const IValueT Registers, CondARM32::Cond Cond);
 
+  void rsb(const Operand *OpRd, const Operand *OpRn, const Operand *OpSrc1,
+           bool SetFlags, CondARM32::Cond Cond);
+
   void sbc(const Operand *OpRd, const Operand *OpRn, const Operand *OpSrc1,
            bool SetFlags, CondARM32::Cond Cond);