[Patch, fortran] PRs 43039, 43 & 44

[Paul Richard Thomas]

Committed as 'obvious' in revision 43039.  I can see no reason for
testcases, since these are all cases of missing checks internal to
gfortran. Not only this, the patch is completely safe since seg faults
or ICEs are prevented without any co-lateral damage.

Paul

2010-03-18  Paul Thomas  <pault@gcc.gnu.org>

        PR fortran/43039
        * trans-expr.c (conv_parent_component_references): Ensure that
	'dt' has a backend_decl.

        PR fortran/43043
        * trans-expr.c (gfc_conv_structure): Ensure that the derived
	type has a backend_decl.

        PR fortran/43044
        * resolve.c (resolve_global_procedure): Check that the 'cl'
	structure is not NULL.