read. (bfd_error_system_call or bfd_error_file_truncated).
* som.c: Do not blindly set bfd_error_system_call after a
failing bfd_read, bfd_write, or bfd_seek. In a few places
(like som_object_p) override the error status set by bfd_read.
* aix386-core.c, aout-encap,c archive.c, bout.c: Likewise.
* coff-rs6000.c, coffgen.c ecoff.c, elf.c: Likewise.
* elf32-hppa.c, elfcode.h, hp300hpux.c, i386lynx.c: Likewise.
* nlm32-alpha.c, nlm32-i386.c, nlm32-sparc.c: Likewise.
* som.c: Check return values from several bfd_{seek,read,write}
calls that we just assumed were not failing.