Configure: Fix MOZ_CAIRO_LIBS/CAIRO_FT_OSLIBS flag processing.

Single quotes used instead of double quotes prevented variable expansion.
[OS/2] Add CHANGES.OS2 file.
Add Build ID to about:buildconfig.

This is to allow for easy identification of the build by the end user.
[OS/2] Update README and CHANGES for release 17.0.5 OS/2 Beta.