issue-511: implemented rel8 jump patching

I've found that Visual Studio 2012 release 32-bit C runtime library
patching fails because array new has rel8 jmp which previous code
could not handle.

Implementation is largely copied from conditional jumps handling code.

Apparently Windows Server 2012 (and presumably windows 8) now has this
form of iat jump. Which is quite useless (rex.w in according to my
understanding is not needed at all) but because of rex.w our code to
recognize jumps like that didn't work.

Fix is just skip this prefix.