Fix android.security.cts.FileDescriptorTest#testCLOEXEC

When ART is mainline, it will create memFd boot-image-methods.art
without MFD_CLOEXEC.
Add MFD_CLOEXEC flag when create boot-image-methods.art memFd.

Bug: 197498527
Test: run cts CtsSecurityTestCases pass

Change-Id: If941c036f7adb598d67ec2b2c5bc4cb24994e3a1
2 files changed