Added a gnatprep file for some tests that need it
Defined fixed array s_timeval_array2
Remove posix.defs for clobber target
Setup gnatmake to use gnat.prep
Fixed parse bug
Define builtin gnatprep values
Enhanced config to allow <gnatprep> section
Added <gnatprep> and fixed Darwin stat(2) call
utime/utimes/stat test