Fortran: parsing issue with DO CONCURRENT;ENDDO on same line [PR120179]

	PR fortran/120179

gcc/fortran/ChangeLog:

	* match.cc (gfc_match_do): Do not attempt to match end-of-statement
	twice.

gcc/testsuite/ChangeLog:

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

(cherry picked from commit 6ce73ad4370c143a7d1e6a13b1d353db5884213f)