re PR ada/16592 (Ada tools don't use the newly built shared libraries)
* s-asthan-vms.adb: Removed.
* s-asthan-vms-alpha.adb: Added.
* Makefile.in [VMS] (LN,LN_S): Define as cp -p
Rename s-asthan-vms.adb to s-asthan-vms-alpha.adb.
[VMS]: Add translations for g-enblsp.adb.
(LIBGNAT_SRCS): Add seh_init.c.
(LIBGNAT_OBJS): Add seh_init.o.
PR ada/16592
Link all gnat tools with -static-libgcc, since
-shared-libgcc is now used by default on some systems (e.g. linux with
recent binutils).
Remove references to Makefile.prolog/generic, no longer used.