In #37718 I already referred you to the documentation about why MacPorts is repeatedly asking you to force the installation of ports, in which the suggested solution is to uninstall MacPorts and all ports, then reinstall. I still recommend you do that, including the part that says "To remove all remaining traces of MacPorts".
The cairo build log that you attached, though incomplete, says "fatal error: 'glib-object.h' file not found
". glib-object.h should of course have been provided by the glib2 port which is a dependency of the cairo port. Please attach a new complete log if you are still experiencing this problem after uninstalling MacPorts and reinstalling.
Also, again, please use WikiFormatting and preview your ticket before submitting it to make sure you got it right.