Merge pull request #140 from Alexpux/develop

 Cherry pick from master
Build shared versions of python dependencies
Move scripts to die function
Interpret parameter #7 for git as branch
If previous download fail remove corrupted file
Fix download marker name
Expat need to GDB and Python. It works in static mode.
Use SRC_DIR_NAME in download marker name.
Move marker to SRCS_DIR
Merge pull request #143 from Alexpux/develop

Some fixes.
Python successfully use static libffi
Update toolchains.
Merge pull request #144 from Alexpux/develop

Static libffi. Update toolchains.
Update libffi to 3.0.12
Merge pull request #145 from Alexpux/develop

Update libffi to 3.0.12
Fix handling of Ctrl-C
* Configure GCC with prefix /mingw{32,64}
* Compress folder without copying
Remove directory only if exists.
Make folder name some shorter
Move GCC libexec directory to lib