Makefile: Support for multiple programs

Add support for compiling multiple programs that use "libjvm.a" so we
can experiment with alternative launcher programs.

Signed-off-by: Pekka Enberg <penberg@kernel.org>
jit: Remove unused function

Signed-off-by: Pekka Enberg <penberg@kernel.org>
jit: Fix jit_magic_trampoline() state check

Signed-off-by: Pekka Enberg <penberg@kernel.org>