Hello,

I upgraded the homebrew packages on my macOS today, and after that could
not build --with-native-compilation any more. It turns out that there is
more than one location for libgccjit.dylib:

---------------------------- Begin Quote -----------------------------
example$ brew ls libgccjit | grep -E 'libgccjit\.(so|dylib)$'
/usr/local/Cellar/libgccjit/12.1.0/lib/gcc/current/libgccjit.dylib
/usr/local/Cellar/libgccjit/12.1.0/lib/gcc/12/libgccjit.dylib
----------------------------- End Quote ------------------------------

This causes MAC_LIBS to end up being set to just '-L' because dirname
throws up an error message when presented with a multi-line string.

The patch below fixes this by simply picking the first line.


Hoping to have helped,

  --alexander