Always use locations from get and put arguments for error messages.

Always use locations from get and put arguments for error messages.

A simple and obvios patch - the error location was taken
from a variable that was not initialized for optional
variables.

gcc/fortran/ChangeLog:

	* check.c (gfc_check_random_seed): Always use locations
	from get and put arguments for error messages.

gcc/testsuite/ChangeLog:

	* gfortran.dg/random_seed_4.f90: New test.