Introduce a new abstract class gfc_dummy_arg that provides a common
interface to both dummy arguments of user-defined procedures (which
have type gfc_formal_arglist) and dummy arguments of intrinsic procedures
(which have type gfc_intrinsic_arg).

gcc/fortran/
	* gfortran.h (gfc_dummy_arg): New.
	(gfc_formal_arglist, gfc_intrinsic_arg): Inherit gfc_dummy_arg.
	(gfc_get_formal_arglist, gfc_get_intrinsic_arg): Call constructor.
	* intrinsic.c (gfc_intrinsic_init_1): Merge the memory area of
	conversion intrinsics with that of regular function and
	subroutine intrinsics.
	Use a separate memory area for arguments.
	(add_sym, gfc_intrinsic_init_1): Don’t do pointer arithmetics
	with next_arg.
	(add_sym, make_alias, add_conv,
	add_char_conversions, gfc_intrinsic_init_1): Call constructor
	before filling object data.
	* resolve.c (resolve_select_type): Same.
---
 gcc/fortran/gfortran.h  | 22 ++++++++++++++-------
 gcc/fortran/intrinsic.c | 44 ++++++++++++++++++++++-------------------
 gcc/fortran/resolve.c   | 10 ++++++----
 3 files changed, 45 insertions(+), 31 deletions(-)