Also define noreturn w/o <stdnoreturn.h> and move it to macro.h instead
of in the testsuite.
Based on similar commit on systemd by Shawn Landden
<shawn@churchofgit.com>.
Functions that always call exit() should be marked with attribute
noreturn. With glibc this is not necessary, but it fails to compile with
uClibc otherwise.
Add trap to stat(): we need to trap other functions too, depending on
stat.h, the function from glibc that is actually called may be stat64 or
__xstat() too.
