This commit changes various pri and pro files to always prepend
the global build output directory (which can be either 'release'
or 'debug', depending on the current build configuration).
Otherwise, if a library that we build ourselves, such as -lspeex in
CONFIG+=bundled-speex, is also available in one of the other lib dirs,
we can't be sure that the one in our build output directory will be used.
This is a problem on FreeBSD, where we add /usr/local/lib
to the QMAKE_LIBDIR in compiler.pri. That directory might contain
its own -lspeex.
With this change, we now prefer libraries in our build output directory
to system libraries.
5cffbf3bd3