Fortran: follow-up fix to checking of renamed-on-use interface name [PR120784]

Commit r16-1633 introduced a regression for imported interfaces that were
not renamed-on-use, since the related logic did not take into account that
the absence of renaming could be represented by an empty string.

	PR fortran/120784

gcc/fortran/ChangeLog:

	* interface.cc (gfc_match_end_interface): Detect empty local_name.

gcc/testsuite/ChangeLog:

	* gfortran.dg/interface_63.f90: Extend testcase.

(cherry picked from commit ddff83b3dde4a8308d0e156f85693e7176b85524)
2 files changed