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.