mingw-cross-compile.sh: Write the build environment to a script
mingw-cross-compile.sh: Write the build environment to a script

The script now writes out a separate script that can be used to set up
the build environment to $ROOT_DIR/share/env.sh. This can be sourced
in a shell to set up the build environment or it can be given a
command to directly execute in the environment. This makes it easier
to build Clutter from your own source rather than checking it out from
git directly.

kerrickstaley/clutter-vala,jigpu/clutter,heysion/clutter-clone,ebassi/clutter,collects/clutter,djdeath/clutter-multithreaded,nobled/clutter,Distrotech/clutter,spatulasnout/clutter,djdeath/clutter,djdeath/clutter,ebassi/clutter,jigpu/clutter,rkudiyarov/clutter_osx,jigpu/clutter,jigpu/clutter,Distrotech/clutter,djdeath/clutter-android,collects/clutter,djdeath/clutter-android,rkudiyarov/clutter_osx,collects/clutter,Distrotech/clutter,djdeath/clutter-multithreaded,heysion/clutter-clone,nobled/clutter,djdeath/clutter-android,dlespiau/clutter,dlespiau/clutter,dlespiau/clutter,rkudiyarov/clutter_osx,rkudiyarov/clutter_osx,heysion/clutter-clone,heysion/clutter-clone,kerrickstaley/clutter-vala,Distrotech/clutter,Distrotech/clutter,djdeath/clutter-android,GNOME/clutter,spatulasnout/clutter,djdeath/clutter-multithreaded,jigpu/clutter,kerrickstaley/clutter-vala,GNOME/clutter,jigpu/clutter,ebassi/clutter,GNOME/clutter,GNOME/clutter,spatulasnout/clutter,Distrotech/clutter,kerrickstaley/clutter-vala,djdeath/clutter,djdeath/clutter-multithreaded,collects/clutter,djdeath/clutter,djdeath/clutter,spatulasnout/clutter,ebassi/clutter,nobled/clutter,GNOME/clutter,djdeath/clutter-android,collects/clutter,heysion/clutter-clone,ebassi/clutter,djdeath/clutter,spatulasnout/clutter