distro-configs: remove no longer working --without-system-cairo

...after 800005b1 "Disallow
--without-system-cairo combined with (implicit) --enable-gtk."

Change-Id: I74f5e4f454f5e1724e258380bbbcd771bf58453a

distro-configs/LibreOfficeLinux.conf

@@ -9,7 +9,6 @@
 --without-system-libxml
 --without-system-jpeg
 --without-system-jars
---without-system-cairo
 --without-system-postgresql
 --without-junit
 --with-help

distro-configs/OxygenOfficeLinux.conf

@@ -56,7 +56,6 @@
 --without-system-libxml
 --without-system-jpeg
 --without-system-jars
---without-system-cairo
 --without-system-mysql
 --without-system-postgresql
 --without-junit