lld-link: Make "duplicate resource" error message a bit more concise

[thakis]

Summary

Reduces the error message from:

lld-link: error: failed to parse .res file: duplicate resource: type STRINGTABLE (ID 6)/name ID 3/language 1033, in test1.res and in test2.res

To:

lld-link: error: duplicate resource: type STRINGTABLE (ID 6)/name ID 3/language 1033, in test1.res and in test2.res

Make sure every error message emitted by cvtres contains the name of at least one ".res" file, so that removing the "failed to parse .res file" string doesn't lose information.

[mstorsjo]

LGTM

COFF/DriverUtils.cpp

MemoryBufferRef convertResToCOFF(ArrayRef<MemoryBufferRef> MBs) {
   object::WindowsResourceParser Parser;
 
   for (MemoryBufferRef MB : MBs) {
     std::unique_ptr<object::Binary> Bin = check(object::createBinary(MB));
     object::WindowsResource *RF = dyn_cast<object::WindowsResource>(Bin.get());
     if (!RF)
       fatal("cannot compile non-resource file as resource");
     if (auto EC = Parser.parse(RF))
-      fatal("failed to parse .res file: " + toString(std::move(EC)));
+      fatal(toString(std::move(EC)));
   }
 
   Expected<std::unique_ptr<MemoryBuffer>> E =
       llvm::object::writeWindowsResourceCOFF(Config->Machine, Parser);
   if (!E)
     fatal("failed to write .res to COFF: " + toString(E.takeError()));
 
   MemoryBufferRef MBRef = **E;