ART: JIT code cache allocation cleanup

Request the data cache with kProtData instead of kProtAll. It isn't
necessary nor intended to be executable. The tail remap for the code
cache will make all required parts executable, if possible.

Also use a unique_ptr to plug a leak on failure.

Bug: 36138508
Test: m
Test: m test-art-host
Test: Test SANITIZE_LITE=true build with wrap.system_server = asanwrapper
Change-Id: Id9e2e51bc8d7a29db99c406cd1e9ef6bbb8d444c