[clang-tidy] Don't run misc-definitions-in-headers check in failing TUs.

[alexfh]

LG

clang-tidy/misc/DefinitionsInHeadersCheck.cpp

Finder->addMatcher(
                   anyOf(usesHeaderFileExtension(HeaderFileExtensions),
                         unless(isExpansionInMainFile())))
             .bind("name-decl"),
         this);
   }
 }
 
 void DefinitionsInHeadersCheck::check(const MatchFinder::MatchResult &Result) {
+  // Don't run the check in failing TUs.
+  if (Result.Context->getDiagnostics().hasErrorOccurred())
+    return;
+
   // C++ [basic.def.odr] p6:
   // There can be more than one definition of a class type, enumeration type,
   // inline function with external linkage, class template, non-static function
   // template, static data member of a class template, member function of a
   // class template, or template specialization for which some template
   // parameters are not specifiedin a program provided that each definition
   // appears in a different translation unit, and provided the definitions
   // satisfy the following requirements.