Make binutils abort message GDB friendly

Make binutils abort message GDB friendly

We used to generate abort messages like:

internal error, aborting at .../bfd/elf64-x86-64.c line 1554 in elf_x86_64_check_relocs

We can't cut and paste "file line ???" to GDB.  This patch changes those
abort messages to

internal error, aborting at .../bfd/elf64-x86-64.c:1554 in elf_x86_64_check_relocs

so that we can cut and paste "file:???" to GDB.

bfd/

	* bfd.c (_bfd_abort): Replace " line " with ":" in output
	message.

gas/

	* messages.c (as_assert): Replace " line " with ":" in output
	message.
	(as_abort): Likewise.

ld/

	* ldmisc.c (ld_abort): Replace " line " with ":" in output
	message.