Predicate hasIncludeGuard
Holds if hf begins with an #ifndef or #if directive ifndef, to test
the macro named includeGuard, and ends with the matching endif.
Import path
import semmle.code.cpp.headers.MultipleInclusionpredicate hasIncludeGuard(HeaderFile hf, PreprocessorDirective ifndef, PreprocessorEndif endif, string includeGuard)