VM: attempt to cancel blocking system calls when ctrl-c is pressed

Windows runs ctrl-c in its own thread and doesn't by itself interrupt
blocking system calls when it is pressed. Therefore you have to manually
send an interrupt signal to the stuck thread.
Windows: Add two new targets, x86-32-vista and x86-64-vista for bjourne's
ctrl-c patch. We still support Windows XP by default for now. Closes
compile.codegen.relocation: make doc example work on 32-bit.