Correct ARM NOP encoding

The encoding of NOP in ARMAsmBackend.cpp is missing a trailing zero, which
causes the emission of a coprocessor instruction rather than "mov r0, r0"
as indicated in the comment.  The test also checks for the wrong encoding.

http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20121203/157919.html

llvm-svn: 169420
diff --git a/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp b/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp
index 3fe23bb..6aab0a0 100644
--- a/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp
+++ b/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp
@@ -220,7 +220,7 @@
 bool ARMAsmBackend::writeNopData(uint64_t Count, MCObjectWriter *OW) const {
   const uint16_t Thumb1_16bitNopEncoding = 0x46c0; // using MOV r8,r8
   const uint16_t Thumb2_16bitNopEncoding = 0xbf00; // NOP
-  const uint32_t ARMv4_NopEncoding = 0xe1a0000; // using MOV r0,r0
+  const uint32_t ARMv4_NopEncoding = 0xe1a00000; // using MOV r0,r0
   const uint32_t ARMv6T2_NopEncoding = 0xe320f000; // NOP
   if (isThumb()) {
     const uint16_t nopEncoding = hasNOP() ? Thumb2_16bitNopEncoding