[COFF] Print the file name on errors writing the pdb file

This avoids confusing contextless error messages such as "No such file
or directory" if e.g. the pdb output file should be written to a
nonexistent directory. (This can happen with linkrepro scripts, at least
old ones.)

Differential Revision: https://reviews.llvm.org/D66466

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@369425 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/COFF/PDB.cpp b/COFF/PDB.cpp
index 1dc1353..25952b5 100644
--- a/COFF/PDB.cpp
+++ b/COFF/PDB.cpp
@@ -1693,6 +1693,7 @@
 }
 
 void PDBLinker::commit(codeview::GUID *guid) {
+  ExitOnError exitOnErr((config->pdbPath + ": ").str());
   // Write to a file.
   exitOnErr(builder.commit(config->pdbPath, guid));
 }