gallium/osmesa: link against static libglapi library too to get the gl exports

gallium/osmesa: link against static libglapi library too to get the gl exports

This should fix missing symbols in a osmesa built against shared glapi
osmesa build. All opengl exports were missing that are defined in the
static glapi, so link against both to fix this.

I could swear I've done this before, maybe there was a glitch in the matrix.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=47824
Cc: "9.2" <mesa-stable@lists.freedesktop.org>
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>