Compiling gdl-0.9rc4 fails with libproj v4.7.0. (http://trac.osgeo.org/proj/)
1) 1st of all, lib is now names libproj.so instead of libproj4.so (need some tweak in configure.in)
2) then, lib_proj.h has been replaced by 4 includes:
3) namespace has changed again and seems to have came back to PJ_init......
PS: I've carefully checked the README in libproj 4.7.0 and the AUUTHORS file includes the original author of libproj4. Thus I'm confident that this release is the newest libproj available (updated on 29-Sep-2009, last CVS commit: 11-May-2010)