Cache flush/invalidate needs RWX permission

When generating JIT code, perform cache maintenance operations before
removing page write permissions. Errata on some cores require data
flush operations to be followed by data invalidate operations
requiring write permission.

Test: ART_TEST_JIT=true test-art-target on an arm64 device.
bug: 27265969

(cherry picked from commit b18a669259aa6ba08d9ca01b5b32c1aa0417138b)

Change-Id: I53080c664f9e7cfebe25f87cf6a45cd6eb33b281
1 file changed