Land rapid7#4434, fix for metasm invalid opcode

Author: Brent Cook

lib/metasm/metasm/cpu/x86_64/opcodes.rb

@@ -61,7 +61,7 @@ def init_x8664_only
 
     addop('movq',  [0x0F, 0x6E], :mrmmmx, {:d => [1, 4]}) { |o| o.args = [:modrm, :regmmx] ; o.props[:opsz] = o.props[:argsz] = 64 }
     addop('movq',  [0x0F, 0x6E], :mrmxmm, {:d => [1, 4]}) { |o| o.args = [:modrm, :regxmm] ; o.props[:opsz] = o.props[:argsz] = 64 ; o.props[:needpfx] = 0x66 }
-    addop('jcxz', [0xE3], nil, :setip, :i8) { |o| o.props[:adsz] = 32 }	# actually 16 (cx), but x64 in general says pfx 0x67 => adsz = 32
+    addop('jecxz', [0xE3], nil, :setip, :i8) { |o| o.props[:adsz] = 32 }	# actually 16 (cx), but x64 in general says pfx 0x67 => adsz = 32
     addop('jrcxz', [0xE3], nil, :setip, :i8) { |o| o.props[:adsz] = 64 }
   end