Remove unused headers

These headers are not supported in mingw, but they do not seem
to be used in any case.

utils/commons.h

@@ -47,18 +47,15 @@
 #include <sys/time.h>
 
 #include <sys/stat.h>
-#include <sys/mman.h>
 #include <fcntl.h>
 #include <unistd.h>
 #include <limits.h>
-#include <pwd.h>
 
 #include <string.h>
 #include <math.h>
 #include <stdarg.h>
 #include <getopt.h>
 
-#include <err.h>
 #include <errno.h>
 #include <assert.h>
 #include <signal.h>