autoconf mess

devel/rudiments
compiles test program to see if mlockall and munlockall exist
prototypes do, but the system calls are stubs only and not in libc
audio/rsynth
  #include "confdefs.h"
  
  int main() { return 0; }
  int t() {
  atan()
   ; return 0; }
print/LPRng-core
configure declares HAVE_DECL_ERRNO
What does the source use? HAVE_ERRNO_DECL!