Clean up unnecessary header includes

Signed-off-by: Christoph Niethammer <niethammer@hlrs.de>

Author: cniethammer

examples/connectivity_c.c

@@ -6,13 +6,9 @@
  * Test the connectivity between all processes.
  */
 
-#include <errno.h>
 #include <mpi.h>
-#include <netdb.h>
 #include <stdio.h>
-#include <stdlib.h>
 #include <string.h>
-#include <unistd.h>
 
 int main(int argc, char **argv)
 {