Fix layering by moving X86DisassemblerDecoderCommon to Support

This is used from llvm tblgen and the X86Disassembler - the only common
library (apart from TableGen, which probably doesn't make sense to have
as a dependency from a release tool (rather than a use-while-building-llvm
tool) of LLVM)

llvm-svn: 328393
diff --git a/llvm/utils/TableGen/DisassemblerEmitter.cpp b/llvm/utils/TableGen/DisassemblerEmitter.cpp
index 6e1d8dd..971ad6a 100644
--- a/llvm/utils/TableGen/DisassemblerEmitter.cpp
+++ b/llvm/utils/TableGen/DisassemblerEmitter.cpp
@@ -74,8 +74,8 @@
 ///     accurate.  Sometimes they are not.
 /// (3) to fix the tables to reflect the actual context (for example, required
 ///     prefixes), and possibly to add a new context by editing
-///     lib/Target/X86/X86DisassemblerDecoderCommon.h.  This is unlikely to be
-///     the cause.
+///     include/llvm/Support/X86DisassemblerDecoderCommon.h.  This is unlikely
+///     to be the cause.
 ///
 /// DisassemblerEmitter.cpp contains the implementation for the emitter,
 ///   which simply pulls out instructions from the CodeGenTarget and pushes them