Change genmodule to parse through the Makefile (or Makefile.am) looking for YASM_MODULES,

Change genmodule to parse through the Makefile (or Makefile.am) looking for YASM_MODULES,
rather than simply taking a list of modules on the command line.  This allows significant
improvement of the behavior when used with Visual Studio, as the "old" way of doing this
with Visual Studio build files was to scan through the .c files; this brought up things
that were actually disabled in the build.

Also incorporate a patch by Charles Bailey to make the VC8 build less noisy, and allow use
of Win32 Bison if it's installed.  Instructions updated as well.

svn path=/trunk/yasm/; revision=1642