* gdb.hp/gen-so-thresh.c, so-thresh.sh, so-thresh.exp,

 	so-thresh.linkopts, so-thresh.mk: Move to gdb.hp from gdb.base
 	(shortening names from solib_threshold.exp etc), won't run on
 	anything but HP-UX for the foreseeable future.
	* gdb.hp/Makefile.in, gdb.base/Makefile.in (clean): Adjust to
 	reflect move.