fortran/
	* gfortran.h (gfc_namespace): Add seen_implicit_none field.
	* symbol.c (gfc_set_implicit_none): Give error if there's a previous
	IMPLICIT NONE, set seen_implicit_none.
	(gfc_merge_new_implicit): Error if there's an IMPLICIT NONE statement.
testsuite/
	* gfortran.dg/implicit_4.f90: New test.

From-SVN: r98952