Android: Fix QCoreApplication::applicationDirPath()

Disable the code path which queries /proc/<pid>/exe for the
current executable path, as from a Q_OS_ANDROID perspective,
this executable will be the Dalvik binary. Instead we
get the application directory via the fallback, by
looking in argv[0], since this is set to the location of the
application binary.

Task-number: QTBUG-32852
Change-Id: Ib93050f41cbd47aaf71284e8bfa6a3247131d978
Reviewed-by: Paul Olav Tvete <paul.tvete@digia.com>