[lld] unified COFF and ELF error handling on new Common/ErrorHandler

Summary:
The COFF linker and the ELF linker have long had similar but separate
Error.h and Error.cpp files to implement error handling. This change
introduces new error handling code in Common/ErrorHandler.h, changes the
COFF and ELF linkers to use it, and removes the old, separate
implementations.

Reviewers: ruiu

Reviewed By: ruiu

Subscribers: smeenai, jyknight, emaste, sdardis, nemanjai, nhaehnle, mgorny, javed.absar, kbarton, fedor.sergeev, llvm-commits

Differential Revision: https://reviews.llvm.org/D39259

llvm-svn: 316624
diff --git a/lld/ELF/InputFiles.cpp b/lld/ELF/InputFiles.cpp
index fb95591..6ced80b 100644
--- a/lld/ELF/InputFiles.cpp
+++ b/lld/ELF/InputFiles.cpp
@@ -8,13 +8,13 @@
 //===----------------------------------------------------------------------===//
 
 #include "InputFiles.h"
-#include "Error.h"
 #include "InputSection.h"
 #include "LinkerScript.h"
 #include "Memory.h"
 #include "SymbolTable.h"
 #include "Symbols.h"
 #include "SyntheticSections.h"
+#include "lld/Common/ErrorHandler.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/CodeGen/Analysis.h"
 #include "llvm/DebugInfo/DWARF/DWARFContext.h"