The mac compiler can't optimize out unused functions.

For some reason "configure" is explicitly NOT passing
LDOPTIMIZE="-Wl,--gc-sections" to the mac build. I don't know why,
but it means the linker includes unused functions in the binary,
and thus complains about unused dependencies being missing.

lib/portability.h

diff --git a/lib/portability.h b/lib/portability.h
index a1dd3a6..7d8334b 100644
--- a/lib/portability.h
+++ b/lib/portability.h
@@ -197,7 +197,7 @@
 #include <sys/personality.h>
 #else
 #define PER_LINUX32 0
-void personality(int x);
+#define personality(x)
 #endif
 
 #if defined(__APPLE__) || defined(__linux__)