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>

zbar.spec

@@ -11,7 +11,6 @@ License:	LGPLv2+
 URL:		http://zbar.sourceforge.net/
 Source0:	https://linuxtv.org/downloads/%{name}/%{name}-%{version}.tar.bz2
 
-BuildRoot:	%{_tmppath}/%{name}-%{version}-%{release}-root-%(%{__id_u} -n)
 
 BuildRequires:	autoconf automake libtool python-devel gettext-devel
 BuildRequires:	qt5-qtbase-devel qt5-qtx11extras-devel