Fix gtk-3-24 builds on older C89-esque compilers
Hi,
The commit 1d62a010 introduced some C99isms in the code, which broke builds on older compilers, so this fixes the builds by:
- Declaring variables at the top of the block.
- Check for
fmin()
and provide a fallback implementation for it if it does not exist.
With blessings, thank you!