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>

lpsolve.spec

@@ -5,7 +5,6 @@ Release:   17%{?dist}
 Source:    http://downloads.sourceforge.net/lpsolve/lp_solve_%{version}_source.tar.gz
 Group:     System Environment/Libraries
 URL:       http://sourceforge.net/projects/lpsolve
-BuildRoot: %{_tmppath}/%{name}-%{version}-%{release}-root-%(%{__id_u} -n)
 License:   LGPLv2+
 
 Patch0:    lpsolve-5.5.0.11.cflags.patch