Move coveragemap_error enum into coverage namespace and InstrProf.h /NFC

llvm-svn: 257295
diff --git a/llvm/lib/ProfileData/CoverageMapping.cpp b/llvm/lib/ProfileData/CoverageMapping.cpp
index 55c0fb4..f5d477b 100644
--- a/llvm/lib/ProfileData/CoverageMapping.cpp
+++ b/llvm/lib/ProfileData/CoverageMapping.cpp
@@ -517,6 +517,6 @@
 
 static ManagedStatic<CoverageMappingErrorCategoryType> ErrorCategory;
 
-const std::error_category &llvm::coveragemap_category() {
+const std::error_category &llvm::coverage::coveragemap_category() {
   return *ErrorCategory;
 }