This patch allows one to place the gcc's liblto_plugin in the lib/bfd-plugins directory
and have it loaded by default (as long as the --target option isn't used).

	PR binutils/14698
	ar.c: Set plugin_target early if plugins are supported.
	nm.c: Likewise.
This fixes a problem building large (> 2Gb) binaries on 32-bit hosts.  Using a
long type instead of long long meant that bfd_seek (SET) could be called with a
negative offset.

	PR ld/16803
	* elf.c (_bfd_elf_set_section_contents): Use correct type to hold
	file position.