[DebugInfo] Common behavior for error types

Following D50807, and heading towards D50664, this intermediary change does the following:

1. Upgrade all custom Error types in llvm/trunk/lib/DebugInfo/ to use the new StringError behavior (D50807).
2. Implement std::is_error_code_enum and make_error_code() for DebugInfo error enumerations.
3. Rename GenericError -> PDBError (the file will be renamed in a subsequent commit)
4. Update custom error messages to follow the same formatting: (\w\s*)+\.
5. Keep generic "file not found" (ENOENT) errors as they are in PDB code. Previously, there used to be a custom enumeration for that purpose.
6. Remove a few extraneous LF in log() implementations. Printing LF is a responsability at a higher level, not at the error level.

Differential Revision: https://reviews.llvm.org/D51499

llvm-svn: 341228
diff --git a/llvm/lib/DebugInfo/MSF/MSFError.cpp b/llvm/lib/DebugInfo/MSF/MSFError.cpp
index 1b8294e..bfac6be 100644
--- a/llvm/lib/DebugInfo/MSF/MSFError.cpp
+++ b/llvm/lib/DebugInfo/MSF/MSFError.cpp
@@ -14,14 +14,12 @@
 using namespace llvm;
 using namespace llvm::msf;
 
-namespace {
 // FIXME: This class is only here to support the transition to llvm::Error. It
 // will be removed once this transition is complete. Clients should prefer to
 // deal with the Error value directly, rather than converting to error_code.
 class MSFErrorCategory : public std::error_category {
 public:
   const char *name() const noexcept override { return "llvm.msf"; }
-
   std::string message(int Condition) const override {
     switch (static_cast<msf_error_code>(Condition)) {
     case msf_error_code::unspecified:
@@ -41,30 +39,8 @@
     llvm_unreachable("Unrecognized msf_error_code");
   }
 };
-} // end anonymous namespace
 
-static ManagedStatic<MSFErrorCategory> Category;
+static llvm::ManagedStatic<MSFErrorCategory> MSFCategory;
+const std::error_category &llvm::msf::MSFErrCategory() { return *MSFCategory; }
 
-char MSFError::ID = 0;
-
-MSFError::MSFError(msf_error_code C) : MSFError(C, "") {}
-
-MSFError::MSFError(const std::string &Context)
-    : MSFError(msf_error_code::unspecified, Context) {}
-
-MSFError::MSFError(msf_error_code C, const std::string &Context) : Code(C) {
-  ErrMsg = "MSF Error: ";
-  std::error_code EC = convertToErrorCode();
-  if (Code != msf_error_code::unspecified)
-    ErrMsg += EC.message() + "  ";
-  if (!Context.empty())
-    ErrMsg += Context;
-}
-
-void MSFError::log(raw_ostream &OS) const { OS << ErrMsg << "\n"; }
-
-const std::string &MSFError::getErrorMessage() const { return ErrMsg; }
-
-std::error_code MSFError::convertToErrorCode() const {
-  return std::error_code(static_cast<int>(Code), *Category);
-}
+char MSFError::ID;