Take a look at
https://aur.archlinux.org/packages/cream-browser/PKGBUILD
, and now take a look at
http://cream-browser.net/
You can see that the PKGBUILD is outdated and need updates to build
correctly Cream-Browser.
It's because the master branch still use cmake and the unstable use a
home-made build system. The branch master, being deprecated, isn't the
default github's branch anymore (so when you clone the repository you
get the unstable branch, for the moment).
I suggests you to not use the PKGBUILD until a stable version is
released and building Cream-Browser yourself ( cf.
http://cream-browser.net
).