[Bug testsuite/78136] New: gcc.dg/cpp/trad/include.c fails with newer glibc versions

["tamar.christina at arm dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78136

            Bug ID: 78136
           Summary: gcc.dg/cpp/trad/include.c fails with newer glibc
                    versions
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: testsuite
          Assignee: unassigned at gcc dot gnu.org
          Reporter: tamar.christina at arm dot com
  Target Milestone: ---

The test gcc.dg/cpp/trad/include.c fails with any glibc versions after commit
6962682ffe5e5f0373047a0b894fee7a774be254.

This commits adds a macro that uses the ## string function which
-traditional-cpp doesn't support.

I'm not quite sure what the intention of the test is.. If it just to test that
-traditional-cpp work and a header file was picked that would always be
available? 

or is it to test glibc compatibility with -traditional-cpp. In the end building
still works, so I assume this test isn't critical. But not sure what should be
done about it.

The source file is compiled with  -traditional-cpp -lm

and the error

Excess errors:
/usr/include/stdlib.h:183:0: error: token "##" is not valid in preprocessor
expressions