Eliminate "const" from extern const to fix breakeage since r135184 on msvc.

MSVC decorates (and distinguishes) "const" in mangler. It brought linkage error between "extern const" declarations and definitions.

llvm-svn: 135269
diff --git a/llvm/lib/Target/MBlaze/Disassembler/MBlazeDisassembler.cpp b/llvm/lib/Target/MBlaze/Disassembler/MBlazeDisassembler.cpp
index 0157b4e..88d80a1 100644
--- a/llvm/lib/Target/MBlaze/Disassembler/MBlazeDisassembler.cpp
+++ b/llvm/lib/Target/MBlaze/Disassembler/MBlazeDisassembler.cpp
@@ -30,7 +30,7 @@
 #include "MBlazeGenEDInfo.inc"
 
 namespace llvm {
-extern const MCInstrDesc MBlazeInsts[];
+extern MCInstrDesc MBlazeInsts[];
 }
 
 using namespace llvm;