Move TargetRegistry.(h|cpp) from Support to MC

This moves the registry higher in the LLVM library dependency stack.
Every client of the target registry needs to link against MC anyway to
actually use the target, so we might as well move this out of Support.

This allows us to ensure that Support doesn't have includes from MC/*.

Differential Revision: https://reviews.llvm.org/D111454

GitOrigin-RevId: 89b57061f7b769e9ea9bf6ed686e284f3e55affe
diff --git a/lib/CodeGen/PPCGCodeGeneration.cpp b/lib/CodeGen/PPCGCodeGeneration.cpp
index f7fc215..3c56dee 100644
--- a/lib/CodeGen/PPCGCodeGeneration.cpp
+++ b/lib/CodeGen/PPCGCodeGeneration.cpp
@@ -31,8 +31,8 @@
 #include "llvm/IRReader/IRReader.h"
 #include "llvm/InitializePasses.h"
 #include "llvm/Linker/Linker.h"
+#include "llvm/MC/TargetRegistry.h"
 #include "llvm/Support/SourceMgr.h"
-#include "llvm/Support/TargetRegistry.h"
 #include "llvm/Target/TargetMachine.h"
 #include "llvm/Transforms/IPO/PassManagerBuilder.h"
 #include "llvm/Transforms/Utils/BasicBlockUtils.h"