include sys/resource.h where needed

We use functions from sys/resource.h in misc applets, but don't include
the header.  This breaks building with newer glibc versions, so add the
include where needed.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

shell/shell_common.c

@@ -18,6 +18,7 @@
  */
 #include "libbb.h"
 #include "shell_common.h"
+#include <sys/resource.h> /* getrlimit */
 
 const char defifsvar[] ALIGN1 = "IFS= \t\n";