Fortran: fix checking of coshape specification in ALLOCATE statement

Fortran: fix checking of coshape specification in ALLOCATE statement

gcc/fortran/ChangeLog:

	PR fortran/105184
	* array.cc (match_subscript): Reject assumed size coarray
	specification with missing lower bound.
	* resolve.cc (resolve_allocate_expr): Fix logic for checking
	allocate-coshape-spec in ALLOCATE statement.

gcc/testsuite/ChangeLog:

	PR fortran/105184
	* gfortran.dg/coarray_44.f90: Adjust expected output.
	* gfortran.dg/coarray_allocate_11.f90: Likewise.
	* gfortran.dg/coarray_allocate_12.f90: New test.