Lands rapid7#4870 by adding two MIPS architectures to the Metasm case statement

Author: HD Moore

lib/msf/core/payload.rb

@@ -552,6 +552,8 @@ def build(asm, off={})
       when ARCH_X64    then Metasm::X86_64.new
       when ARCH_PPC    then Metasm::PowerPC.new
       when ARCH_ARMLE  then Metasm::ARM.new
+      when ARCH_MIPSLE  then Metasm::MIPS.new(:little)
+      when ARCH_MIPSBE  then Metasm::MIPS.new(:big)
       else
         elog("Broken payload #{refname} has arch unsupported with assembly: #{module_info["Arch"].inspect}")
         elog("Call stack:\n#{caller.join("\n")}")