Comment 4 for bug 716417

I got the compilation to go through by changing buildenv file to add -D_XPG6 like this:

CC = cc -std=c99 -D_XPG6

Frankly, I don't know what that flag means, but I just thought of adding it bypass the check in /usr/include/sys/feature_tests.h where it triggers this error. I hope this information is useful to figure out a proper fix.