New java class initialization code in compiler

[Anthony Green]

I've committed my changes to initialize java classes via the .jcr section.
Make sure you do a fresh build of the compiler.  I'm not convinced the
dependencies for crtbegin and crtend are set up properly.

One side effect of this change is that a weak reference to
_Jv_RegisterClasses will be found in every program and shared library built
by GCC (on platforms using .jcr section initialization).  I find this
amusing.

I don't think it will cause problems for C/C++ programs using their own
definition of _Jv_RegisterClasses, as it will only be called if the .jcr
section also contains some non-zero value.

AG