neotools is missing the errno.h include in the md3.c source. I'm providing a fix
Created attachment 77079 [details, diff] neotools-0.8.1-errno.patch Adding #include <errno.h> to md3.c
Created attachment 77080 [details, diff] neotools-0.8.1.ebuild applying the previous patch
Fixed in CVS, and bumped to 0.8.2