Cleanup LLVMMC headers

There's a few relevant forward declarations in there that may require downstream
adding explicit includes:

llvm/MC/MCContext.h no longer includes llvm/BinaryFormat/ELF.h, llvm/MC/MCSubtargetInfo.h, llvm/MC/MCTargetOptions.h
llvm/MC/MCObjectStreamer.h no longer include llvm/MC/MCAssembler.h
llvm/MC/MCAssembler.h no longer includes llvm/MC/MCFixup.h, llvm/MC/MCFragment.h

Counting preprocessed lines required to rebuild llvm-project on my setup:
before: 1052436830
after:  1049293745

Which is significant and backs up the change in addition to the usual benefits of
decreasing coupling between headers and compilation units.

Discourse thread: https://discourse.llvm.org/t/include-what-you-use-include-cleanup
Differential Revision: https://reviews.llvm.org/D119244

1 files changed, 3 insertions, 2 deletions

diff --git a/llvm/lib/MC/MCWin64EH.cpp b/llvm/lib/MC/MCWin64EH.cpp
index 2a93c35..5956b3a 100644
--- a/llvm/lib/MC/MCWin64EH.cpp
+++ b/llvm/lib/MC/MCWin64EH.cpp
@@ -10,12 +10,13 @@
 #include "llvm/ADT/Twine.h"
 #include "llvm/MC/MCContext.h"
 #include "llvm/MC/MCExpr.h"
-#include "llvm/MC/MCObjectFileInfo.h"
 #include "llvm/MC/MCObjectStreamer.h"
-#include "llvm/MC/MCSectionCOFF.h"
 #include "llvm/MC/MCStreamer.h"
 #include "llvm/MC/MCSymbol.h"
 #include "llvm/Support/Win64EH.h"
+namespace llvm {
+class MCSection;
+}
 
 using namespace llvm;