CI: MinGW environments can no longer link against Graphviz libraries
As demonstrated here: https://gitlab.com/smattr/graphviz/-/pipelines/880696293
+ cc -std=c99 C:/GitLab-Runner/builds/smattr/graphviz/tests/2272.c -o C:/msys64/tmp/tmp_dd_fb7c/a.exe '-IC:\Graphviz\include' '-LC;C:\msys64\Graphviz\lib' -lcgraph -lgvc
---------------------------- Captured stderr call -----------------------------
C:/msys64/mingw32/bin/../lib/gcc/i686-w64-mingw32/13.1.0/../../../../i686-w64-mingw32/bin/ld.exe: cannot find -lcgraph: No such file or directory
C:/msys64/mingw32/bin/../lib/gcc/i686-w64-mingw32/13.1.0/../../../../i686-w64-mingw32/bin/ld.exe: cannot find -lgvc: No such file or directory
collect2.exe: error: ld returned 1 exit status