Disable XOM on libraries for apps with targetSdkVerison<Q

Apps may (and do) assume that libraries are readable. To avoid app
breakage, mark execute-only sections of as read+execute
for apps with targetSdkVersion<Q.

Bug: 128907672
Test: Check libc for app with targetSdk==current
cat /proc/25950/maps | grep libc.so
77c01e3000-77c028b000 --xp 00041000 07:20 106 /apex/com.android.runtime/lib64/bionic/libc.so
Test: Check libc for app with targetSdk<current
cat /proc/26355/maps | grep libc.so
77c01e3000-77c028b000 r-xp 00041000 07:20 106
/apex/com.android.runtime/lib64/bionic/libc.so

Change-Id: I90b5c91923c8008ae4b4818985842fe3e354a850