Fix readonly for android

The hasmntopt() function doesn't exist in android, so it needs to be
defined if we are building for android.  Also, MNTOPT_RO isn't defined
on android (and maybe others), so we need to manually specify if if it
isn't already defined.

Change-Id: I55330e37cebc087e138cdf6a0cbbe61df59f55fa
1 file changed