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>

ilbc.spec

@@ -15,7 +15,6 @@ Patch3:		ilbc-0003-Suppress-warning-about-unused-parameter-s.patch
 BuildRequires:	autoconf
 BuildRequires:	automake
 BuildRequires:	libtool
-BuildRoot:	%(mktemp -ud %{_tmppath}/%{name}-%{version}-%{release}-XXXXXX)
 
 
 %description