java.so: Fix JavaVMOption initialization

JavaVMOption has extraInfo member that's not initialized in mkoption().
It only used by few special case options that provide a function pointer
hook to the JVM so it's harmless but fix it anyway.

Spotted by Coverity.

Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>
elf: Fix assert() in object::relocate_pltgot

The assertion in object::relocate_pltgot uses assignment instead of
comparison.  Fix that up.

Spotted by Coverity.

Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>