Remove BuildRoot definition

None of currently supported distributions need that.
It was needed last for EL5 which is EOL now

Signed-off-by: Igor Gnatenko <ignatenkobrain@fedoraproject.org>

evolution-data-server.spec

@@ -37,7 +37,6 @@ Group: System Environment/Libraries
 Summary: Backend data server for Evolution
 License: LGPLv2+
 URL: https://wiki.gnome.org/Apps/Evolution
-BuildRoot: %(mktemp -ud %{_tmppath}/%{name}-%{version}-%{release}-XXXXXX)
 Source: http://download.gnome.org/sources/%{name}/3.27/%{name}-%{version}.tar.xz
 
 Provides: evolution-webcal = %{version}