[llvm-objdump][COFF][NFC] Split format-specific interfaces; add namespace

Summary:
This patch addresses, for the interfaces implemented by `COFFDump.cpp`,
multiple issues identified with the current structure of
`llvm-objdump.h` in the review of D72973.

This patch moves implementation details of the tool into an
`llvm::objdump` namespace for external linkage names, splits the
implementation details into separate headers for each implementation
file, and uses qualified names when declaring members of the
`llvm::objdump` namespace in place of leaving the namespace definition
open.

Reviewers: jhenderson, DiggerLin, jasonliu, daltenty, MaskRay

Reviewed By: jhenderson, MaskRay

Subscribers: MaskRay, rupprecht, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D77285

1 files changed, 2 insertions, 0 deletions

diff --git a/llvm/tools/llvm-objdump/llvm-objdump.cpp b/llvm/tools/llvm-objdump/llvm-objdump.cpp
index 4d5e09f..6f28415 100644
--- a/llvm/tools/llvm-objdump/llvm-objdump.cpp
+++ b/llvm/tools/llvm-objdump/llvm-objdump.cpp
@@ -16,6 +16,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm-objdump.h"
+#include "COFFDump.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SetOperations.h"
@@ -72,6 +73,7 @@
 #include <utility>
 
 using namespace llvm::object;
+using namespace llvm::objdump;
 
 namespace llvm {