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>

libtiger.spec

@@ -7,7 +7,6 @@ Group:          System Environment/Libraries
 License:        LGPLv2+
 URL:            http://libtiger.googlecode.com
 Source0:        http://libtiger.googlecode.com/files/libtiger-%{version}.tar.gz
-BuildRoot:      %{_tmppath}/%{name}-%{version}-%{release}-root-%(%{__id_u} -n)
 
 BuildRequires:  libkate-devel >= 0.2.7
 BuildRequires:  pango-devel