Does not build on OS X

[qu1j0t3]

Tested: Mojave 10.14.6

The build ends without producing a binary. Having inspected the output of make -d I believe this is due to the dependency on NetPBM.

There may also be an issue with header dep generation as it silently generates an incorrect tumble_pbm.d?

A common way of providing dependencies on OS X is through Mac Homebrew. (https://brew.sh/)

Unfortunately Homebrew does not put the netpbm installation files in a useful or version independent location on my system, I am not sure why (brew link [-f] netpbm does not do it). If it did, it would be possible to use pkg-config to provide correct cpp and link flags to this build.

Let me know if you are interested in having me debug this further, at the moment it seems to me that Homebrew is the blocker to a clean build recipe.

A workaround on my system right now is changing line 105:

CFLAGS := $(CFLAGS) $(CDEFINES) -I/usr/local/Cellar/netpbm/10.86.23/include/netpbm/

This assumes brew install netpbm has been done, and the actual versioned path checked with brew list netpbm.

[brouhaha]

I'd certainly prefer to use pkg-config. I'd rather not put paths like /usr/local into the Makefile. Is it typical with Homebrew packages to put things in /usr/local?