Bug#534287: Allows upgrades which break new .pc files.

["Trent W. Buck" <trentbuck@gmail.com>]

Package: libglu1-mesa-dev
Version: 7.4.1-1
Severity: minor

It seems that the X11 libraries in unstable (7.4) have pkg-config
integration that wasn't in the testing version (7.0).  But I can
*accidentally* upgrade only some libraries, and thus get a system that
has .pc files that don't work.

Perhaps the 7.4 libraries should have Depends: ... (>= 7.4)?

Here is a reproduction of the error I caused accidentally.

    $ aptitude search -F%p%v ~i~nlibgl.?1-mesa-dev
    libgl1-mesa-dev                                           7.0.3-7
    libglu1-mesa-dev                                          7.0.3-7
    $ pkg-config --cflags --libs glu
    Package glu was not found in the pkg-config search path.
    Perhaps you should add the directory containing `glu.pc'
    to the PKG_CONFIG_PATH environment variable
    No package 'glu' found

    $ sudo aptitude install libglu1-mesa-dev/unstable -y
    [...]
    $ aptitude search -F%p%v ~i~nlibgl.?1-mesa-dev
    libgl1-mesa-dev                                           7.0.3-7
    libglu1-mesa-dev                                          7.4.1-1
    $ pkg-config --cflags --libs glu
    Package gl was not found in the pkg-config search path.
    Perhaps you should add the directory containing `gl.pc'
    to the PKG_CONFIG_PATH environment variable
    Package 'gl', required by 'glu', not found

    $ sudo aptitude install libgl1-mesa-dev/unstable -y
    [...]
    $ aptitude search -F%p%v ~i~nlibgl.?1-mesa-dev
    libgl1-mesa-dev                                           7.4.1-1
    libglu1-mesa-dev                                          7.4.1-1
    $ pkg-config --cflags --libs glu
    Package xext was not found in the pkg-config search path.
    Perhaps you should add the directory containing `xext.pc'
    to the PKG_CONFIG_PATH environment variable
    Package 'xext', required by 'gl', not found
    $