I have complied r.in.tiff only (not r.out.tiff) on Solaris 2.3. You need to
either compile with SYSV or edit the libtiff/tiffcompat.h for the SYSV part.
Then, take out the r.out.tiff compilation part in the tools/Gmakefile, that is,
everything related to PGM1. This works for me.
Yung-Tsung Kang,
Center for Remote Sensing, Michigan State University