Another major refactoring, to split up cross host/target.

Another major refactoring, to split up cross host/target.

Primary testing so far is for SVM.  To build SVM from 9.2 x86-64, do the
following:

1. Generate a new build with an SVM compiler:
     ./configure --with-compiler-target=svm
     make

2. Create a second build configured with:
     ./configure --enable-native-code=svm --enable-cross-compiling
     make
     make cross-target