#14 constructor/destructor attributes for gcc in lieu of DllMain

[Stephen Crowley]

After much cursing and frustration, I discovered that onProcessCreation/Destruction must be called, and that only happens for windows platforms (see os_dep.cpp).

The solution is to use gcc's constructor/destructor attributes. This patch does that.

Also, this patch fixes the fact that the single-string constructor of JClassImpl doesn't initialize mClass to 0

[Stephen Crowley]

patch to declare onProcessCreation and onProcessDestruction as constructors/destructors via attributes for gcc