Transfer ClassLoaderContext to the caller of OatFileAssistant::Create.

mast@ pointed out that the owned object adds complexity to
OatFileAssistant. Full discussion here: ag/19066608.

Bug: 229268202
Test: m test-art-host-gtest-art_runtime_tests
Change-Id: Iadcd5f5f090808d8dbbb6449ba9fc32832d99756
Merged-In: Ia8f320d1375985bbb6239822a90e6f95a9774bb5
3 files changed