gdb/

gdb/
	Fix duplicate .o files after omitting libbfd.a.
	* Makefile.in (ALL_TARGET_OBS): Remove corelow.o.
	(SFILES): Add corelow.c.
	(COMMON_OBS): Add corelow.o.
	(ALLDEPFILES): Remove corelow.c.
	* config/alpha/alpha-linux.mh (NATDEPFILES): Remove corelow.o.
	* config/alpha/alpha-osf3.mh: Likewise.
	* config/alpha/fbsd.mh: Likewise.
	* config/arm/nbsdaout.mh: Likewise.
	* config/arm/nbsdelf.mh: Likewise.
	* config/i386/i386gnu.mh: Likewise.
	* config/ia64/hpux.mh: Likewise.
	* config/ia64/linux.mh: Likewise.
	* config/m32r/linux.mh: Likewise.
	* config/m68k/linux.mh: Likewise.
	* config/mips/irix5.mh: Likewise.
	* config/mips/irix6.mh: Likewise.
	* config/pa/hpux.mh: Likewise.
	* config/pa/linux.mh: Likewise.
	* config/powerpc/aix.mh: Likewise.
	* config/sparc/linux.mh: Likewise.
	* config/sparc/linux64.mh: Likewise.
	* config/sparc/sol2.mh: Likewise.
	* config/vax/vax.mh: Likewise.
	* configure.tgt (alpha*-*-freebsd* alpha*-*-kfreebsd*-gnu)
	(alpha*-*-netbsd*, alpha*-*-knetbsd*-gnu, alpha*-*-openbsd*)
	(am33_2.0*-*-linux*, arm*-wince-pe, arm*-*-mingw32ce*, arm*-*-linux*)
	(arm*-*-openbsd*, cris*, frv-*-*, hppa*-*-hpux*, hppa*-*-netbsd*)
	(hppa*-*-openbsd*, i[34567]86-*-dicos*, i[34567]86-*-freebsd*)
	(i[34567]86-*-kfreebsd*-gnu, i[34567]86-*-netbsd*)
	(i[34567]86-*-knetbsd*-gnu, i[34567]86-*-openbsd*, i[34567]86-*-nto*)
	(i[34567]86-*-solaris2.1[0-9]*, x86_64-*-solaris2.1[0-9]*)
	(i[34567]86-*-solaris*, i[34567]86-*-linux*, i[34567]86-*-cygwin*)
	(i[34567]86-*-mingw32*, m68*-*-netbsd*, m68*-*-knetbsd*-gnu)
	(m68*-*-openbsd*, m88*-*-openbsd*, microblaze*-linux-*)
	(microblaze*-*-linux*, mips*-*-linux*, mips*-*-netbsd*)
	(mips*-*-knetbsd*-gnu, mips64*-*-openbsd*, powerpc-*-netbsd*)
	(powerpc-*-knetbsd*-gnu, powerpc-*-openbsd*, powerpc-*-linux*)
	(powerpc64-*-linux*, s390*-*-*, score-*-*, sh*-*-linux*)
	(sh*-*-netbsdelf*, sh*-*-knetbsd*-gnu, sh*-*-openbsd*)
	(sparc*-*-freebsd*, sparc*-*-kfreebsd*-gnu, sparc-*-netbsd*)
	(sparc-*-knetbsd*-gnu, sparc64-*-netbsd*, sparc64-*-knetbsd*-gnu)
	(sparc-*-openbsd*, sparc64-*-openbsd*, tic6x-*-*linux, vax-*-netbsd*)
	(vax-*-knetbsd*-gnu, vax-*-openbsd*, x86_64-*-dicos*, x86_64-*-linux*)
	(x86_64-*-freebsd*, x86_64-*-kfreebsd*-gnu, x86_64-*-netbsd*)
	(x86_64-*-knetbsd*-gnu, x86_64-*-openbsd*, xtensa*-*-linux*): Remove
	corelow.o from gdb_target_obs.
	* corefile.c (core_target): Update the comment on NULL value.
	(core_file_command): Replace error by gdb_assert on CORE_TARGET.
	* corelow.c (sniff_core_bfd): Call error instead of warning on zero
	MATCHES.  Drop YUMMY set on NULL.
	(core_close): Do not call exit_inferior_silent on zero PID.  Do not
	reclaim CORE_DATA if it is already NULL.