Not entirely sure this question should be posted here, but given that the wiki gives instructions on how to do it, and at least part of the code was written by Frank, I'm taking a leap. Sorry if it's the wrong place.
So, the wiki states that building for 12-bits is just a matter of defining BITS_IN_JSAMPLE to 12, and defining NEED_12_BIT_NAMES. I did so, but while running make, the wrtarga.c file accuses an error: "Sorry, this code only copes with 8-bit JSAMPLEs. /* deliberate syntax err */", and this is breaking the build.
I'm using the latest release from http://www.ijg.org/files/. Now, the wiki states that support for 12-bit JPEG is a branch that was never implemented on main trunk, and that I should get this version from maptools.org, but that website seems to not have been updated in a long while, so I'm somewhat sketchy of it.
Is it still so that a branch is needed? If so, where to get it? If not, what to do about the error? I frankly could do without Targa support, if need be. There is a "without-package" flag in the configure file, would this be the way?