Fix to actually load the real libGL.so when the application asks for it.

Fix to actually load the real libGL.so when the application asks for it.

Our wrapper library intercepts calls to dlopen "libGL.so" and returns
a handle to itself. That's correct, and as intended.

Before doing this, however, it's essential to actual dlopen "libGL.so"
for real even though we won't be returning a handle to it. This
ensures that any side effects from that dlopen are taken care of.

This fixes a bug where "fips apitrace replay foo.trace" would cause
Mesa to fail to load its driver as follows (with LIBGL_DEBUG=verbose):

libGL: OpenDriver: trying .../lib/dri/i965_dri.so
libGL error: dlopen .../lib/dri/i965_dri.so failed (.../lib/libdricore9.2.0.so.1: undefined symbol: _glapi_tls_Context)