JIT: Separate code allocation and initialization.

Allocate(reserve) both code and data first,
and then initialise(commit) both of them.

This is useful since we know the address sooner
for the purpose of debug info generation.

Test: ./art/test.py -b -r --jit --host --64
Change-Id: I4971a8801004efbc6c2b27884834dda775b72664
6 files changed