libxul memory mappings are not always merged correctly on Android

[gabrielesvelto]

When we encounter an executable mapped like this:

7f4d81103000-7f4d83153000 r--p 00000000 fd:20 7323                       /data/app/org.mozilla.geckoview.test_runner-1/lib/x86_64/libxul.so
7f4d83153000-7f4d83154000 r--p 02050000 fd:20 7323                       /data/app/org.mozilla.geckoview.test_runner-1/lib/x86_64/libxul.so
7f4d83154000-7f4d84b8d000 r--p 02051000 fd:20 7323                       /data/app/org.mozilla.geckoview.test_runner-1/lib/x86_64/libxul.so
7f4d84b8d000-7f4d84b91000 ---p 00000000 00:00 0
7f4d84b91000-7f4d8e031000 r-xp 03a8a000 fd:20 7323                       /data/app/org.mozilla.geckoview.test_runner-1/lib/x86_64/libxul.so
7f4d8e031000-7f4d8e034000 ---p 00000000 00:00 0
7f4d8e034000-7f4d8e62d000 r--p 0cf29000 fd:20 7323                       /data/app/org.mozilla.geckoview.test_runner-1/lib/x86_64/libxul.so
7f4d8e62d000-7f4d8e630000 ---p 00000000 00:00 0
7f4d8e630000-7f4d8e6c7000 rw-p 0d521000 fd:20 7323                       /data/app/org.mozilla.geckoview.test_runner-1/lib/x86_64/libxul.so

We don't merge it correctly, instead we generate two modules, one covering the first three non-executable mappings and one covering everything from the executable mapping and the last one. See also bug 1935408 on our bug tracker for more details.