Fix setting FdFile::ReadOnlyMode() flag

The Unix flag O_RDONLY is defined as zero and hence its presence
cannot be tested with '(flags & O_RDONLY) != 0'. This used to be
broken in FdFlag when setting its internal `read_only_mode_` flag.

Test: m test-art-host-gtest-fd_file_test
Change-Id: Ib48abfc908c7032f031450a1574130e06f6c3bab
3 files changed