Remove obsolete support for ADA_LONG_TYPE_SIZE

The macro was only defined for VMS and VMS is no longer supported in Ada.

gcc/
	* config/vms/vms.h (ADA_LONG_TYPE_SIZE): Delete.
	* doc/tm.texi.in (ADA_LONG_TYPE_SIZE): Likewise.
	* doc/tm.texi: Regenerate.
	* system.h (ADA_LONG_TYPE_SIZE): Poison.

gcc/ada/
	* gnatlink.adb: Remove clause for System.CRTL.
	(Store_File_Context): Remove clause for System.CRTL.long.
	* gcc-interface/targtyps.cc (ADA_LONG_TYPE_SIZE): Delete.
	(get_target_long_size): Use LONG_TYPE_SIZE.
	* libgnat/i-c.ads: Remove clause for System.Parameters.
	(long): Declare as derived from Long_Integer.
	* libgnat/i-cstrin.ads: Add clause for System.Parameters.
	* libgnat/s-crtl.ads: Remove clause for System.Parameters.
	(long): Declare as subtype of Long_Integer.
	* libgnat/s-parame.ads (long_bits): Delete.
	* libgnat/s-parame__hpux.ads (long_bits): Likewise.
	* libgnat/s-parame__vxworks.ads (long_bits): Likewise.