liblauncher doesn't build on Fedora 13 (implicit DSO linking)

[Mathieu Bridon]

Since Fedora 13, we changed the way we handle implicit DSO linking:
    http://fedoraproject.org/wiki/Features/ChangeInImplicitDSOLinking

To make it short (and probably half-true), libs must now be specified explicitly to the linker. More complete informations available at the above feature page or below:
    https://fedoraproject.org/wiki/UnderstandingDSOLinkChange

Because of that, building liblauncher fails on Fedora 13 with the following error message:
  LINK test-liblauncher
/usr/bin/ld: test_liblauncher-test-liblauncher.o: undefined reference to symbol 'gtk_init'
/usr/bin/ld: note: 'gtk_init' is defined in DSO /usr/lib64/libgtk-x11-2.0.so.0 so try adding it to the linker command line
/usr/lib64/libgtk-x11-2.0.so.0: could not read symbols: Invalid operation
collect2: ld returned 1 exit status
make[2]: *** [test-liblauncher] Error 1
make[1]: *** [all-recursive] Error 1
make: *** [all] Error 2
error: Bad exit status from /var/tmp/rpm-tmp.ukjQHw (%build)

[Mathieu Bridon (bochecha)]

Attached patch allows building liblauncher.

Courtesy of Pikachu_2014 of #fedora-fr fame.