This unit test verifies that entrypoint patching works as expected, by
loading libGLX_patchentry.so, looking up the address of
__glXSawVertex3fv defined in libGLX_patchentry.so, and verifying that
the value at this symbol matches the number of calls to glVertex3fv()
(which is hacked to increment __glXSawVertex3fv via entrypoint
rewriting).
