Various fixes for install_deps' scons options.
Also svn-ignore BUILD_NOTES.txt generated file.

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@57128 954f8c5b-7b00-dc11-b283-0030488c597c
Grr, forgot this in r57127... 
BF_PYTHON_INC can contain more than one path (in the mono-string format), don't know how this could not be found earlier, completely broke build of GE on any recent Debian/Ubuntu distro???

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@57129 954f8c5b-7b00-dc11-b283-0030488c597c