Fortran/OpenMP: Split-off resolve_omp_allocate_clauses

Move the code for ALLOCATE clause checking out of resolve_omp_clauses into
a new function. Additionally, the all-enclosing if condition block is
replaced by an early return; likewise, an inner if condition block that
stretched to the end of the outer one is replaced by a second early
return. Hence, a lot of code could be shifted 4 or 8 columns to the left.

Except for the re-indentation, the early exit changes to the two if
conditions and to two variable declarations, the code is identical.

gcc/fortran/ChangeLog:

	* openmp.cc (resolve_omp_allocate_clauses): New function for
	resolving 'allocate' clauses, splitt-off from ...
	(resolve_omp_clauses): ... here. Call the new function.

Suggested-by: Julian Brown <julian@codesourcery.com>