Move contrib/top/top.X to contrib/top/top.xs and move

contrib/top/top.local.H to contrib/top/top.local.hs.
This fixes a build breakage when src is on a case-
insensitive file system -- we never properly create
top.x nor top.local.h. Change the makefile accordingly.

MFC after:	3 days

usr.bin/top/Makefile

@@ -30,8 +30,8 @@ sigdesc.h: ${SIGCONV_AWK} ${SIGNAL_H}
 	awk -f ${SIGCONV_AWK} < ${SIGNAL_H} > ${.TARGET}
 
 CLEANFILES+= top.local.h top.x
-.SUFFIXES: .X .x .H .h
-.X.x .H.h:
+.SUFFIXES: .xs .x .hs .h
+.xs.x .hs.h:
 	@${ECHO} Making ${.TARGET} from ${.IMPSRC}
 	@sed -e's,%LoadMax%,5.0,g' \
 	-e's,%TableSize%,20011,g' \