Add missing require

MSP-11145

Author: limhoff-r7

modules/exploits/linux/local/pkexec.rb

@@ -3,6 +3,12 @@
 # Current source: https://github.com/rapid7/metasploit-framework
 ##
 
+#
+# Project
+#
+
+require 'msf/core/exploit/local/linux'
+
 class Metasploit4 < Msf::Exploit::Local
   Rank = GreatRanking