Support passing --library=lib<foo>.la

Support passing --library=lib<foo>.la

In addition to the current --library=<foo>, support --library=lib<foo>.la.
This makes it unambiguous that we are referencing an uninstalled
library and allows accurate extraction of the shared library name
for the uninstalled library.

* tests/scanner/Makefile.am tests/offsets/Makefile.am: Use the
  new form of --library=. Also some LD_LIBRARY_PATH frobbing as needed.

*-expected.gir *-expected.tgir: We now pick out the shared library
  accurately, so fix shared-library="" in our reference girs. (The
  comparison may need some pre-sanitization now to work on non-ELF)

http://bugzilla.gnome.org/show_bug.cgi?id=591669