Let GNU ld be less obscure about missing symbols and DSOs.  If the BFD
object looks like a typical shared library, suggest adding '-l<foo>',
where <foo> has the 'lib' prefix and '.so<bar>' or '.a' suffix removed.

Otherwise, suggest adding '-l:<foo>', where <foo> is the full DT_SONAME.

Submitted by:	Conrad Meyer <conrad.meyer@isilon.com>
Sponsored by:	EMC / Isilon storage division
Reviewed by:	emaste
PR:		194296
MFC after:	1 week
Differential Revision: https://reviews.freebsd.org/D1152