build-sys: C99 has true and false

It is pointless to define true and false when standard headers can do
that.

Signed-off-by: Sami Kerola <kerolasa@iki.fi>

src/other.c

@@ -52,6 +52,7 @@ extern char *malloc();
 
 #include <err.h>
 #include <errno.h>
+#include <stdbool.h>
 #include <stddef.h>
 #include <stdio.h>