build: pick up the JS library from pkg-config instead of the system one
build: pick up the JS library from pkg-config instead of the system one

Add JS_LIBS to gjs_console_LDADD so that the JS library in libdir from
pkg-config is picked up first instead of the library in /usr/lib which may be
from a system install of an older spidermonkey.

https://bugzilla.gnome.org/show_bug.cgi?id=644971

magcius/gjs,djdeath/gjs,djdeath/gjs,mtwebster/cjs,mtwebster/cjs,endlessm/gjs,pixunil/cjs,mtwebster/cjs,endlessm/gjs,endlessm/gjs,magcius/gjs,pixunil/cjs,pixunil/cjs,djdeath/gjs,djdeath/gjs,pixunil/cjs,mtwebster/cjs,pixunil/cjs,magcius/gjs,djdeath/gjs,magcius/gjs,magcius/gjs,endlessm/gjs,endlessm/gjs,mtwebster/cjs