This results in size savings for thirdparty libraries that are only used once, and a size increase for libraries used more than once (eg. OpenSSL). More importantly, it prevents conflicts with other versions of the libraries loaded by other Python modules, such as the version of OpenSSL that the hmac module uses.
We need to be careful to only apply this for packages that are either used once, used in a plug-in module, or if we don't need to pass thirdparty library structures across Panda library boundaries. For example, I haven't done this for Bullet, since the Bullet symbols need to be available through libpandabullet.so due to the fact that pandabullet contains calls to the Bullet libraries in the inline methods.
Fixes#851
e78ce78acf
