Add methods to get jumpsToLink/unlinkedCode for ARM_THUMB2

Needed to save/load when compiling/loading seperately.
Split Assembler::link into prelink and link

The prelink part setup jumps before the link part does the linking. To get the
correct links we need to extract them between calling prelink and link so that's
the reason.

For code that doesn't call prelink, only link things will keep working
Merge pull request #4 from meltingsnowman/armthumb2_changes

Armthumb2 changes qt 5.3.1