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>

schroedinger.spec

@@ -10,7 +10,6 @@ Group:          System Environment/Libraries
 License:        GPL+ or LGPLv2+ or MIT or MPLv1.1
 URL:            http://www.diracvideo.org/
 Source0:        http://www.diracvideo.org/download/schroedinger/schroedinger-%{version}.tar.gz
-BuildRoot:      %{_tmppath}/%{name}-%{version}-%{release}-root-%(%{__id_u} -n)
 
 BuildRequires:  orc-devel >= 0.4.16
 BuildRequires:  glew-devel >= 1.5.1