[Mono-dev] Mono build changes to support sgen.

[Miguel de Icaza]

If you build Mono from trunk on Linux or Darwin on x86, x86-64, PowerPC
or ARM you will now get two binaries at the end of the build process:
mono and mono-sgen.

mono-sgen is a version of the Mono runtime that has been compiled with
support for SGen.   

The build times will take a bit longer, but it will help us quickly test
the new garbage collector by installing both the current VM as well as
the sgen-based VM side-by-side.

The only problem with this patch is that now bootstraps no longer use
sgen.   Not quite sure what to do about this.

If you do not want to build the 2 mono runtimes and the two sets of
embeddable Mono libraries, you can use:

	./configure --with-sgen=no

Miguel.