cpukit/libmisc/shell/main_mknod.c: Address -Wclobbered warning

This warning indicates the potential for using a local variable which
is not guaranteed to be preserved across a setjmp()/longjmp() pair.
In this case, it was a false positive and the warning was disabled.

Updates #5364.

cpukit/libmisc/shell/main_mknod.c

@@ -100,6 +100,9 @@ rtems_shell_mknod_exit (rtems_shell_mknod_globals* globals, int code)
 
 #include "mknod-pack_dev.c"
 
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wclobbered"
+
 static int
 rtems_shell_main_mknod(int argc, char *argv[])
 {
@@ -112,6 +115,8 @@ rtems_shell_main_mknod(int argc, char *argv[])
   return mknod_globals.exit_code;
 }
 
+#pragma GCC diagnostic pop
+
 #define getprogname() "mknod"
 
 #ifdef KERN_DRIVERS