Fix few issues according to fedora packaging guidelines

* Sources used to build the package match the upstream source, as
     provided in the spec URL
* Package does not run rm -rf %{buildroot} (or $RPM_BUILD_ROOT) at the
     beginning of %install.
* Buildroot is not present
     Note: Buildroot: present but not needed
* Package has no %clean section with rm -rf %{buildroot} (or
             $RPM_BUILD_ROOT)
     Note: %clean present but not required
* remove unused build dependency on autoconf

libtalloc.spec

@@ -10,11 +10,9 @@ Release: 3%{?dist}
 Group: System Environment/Daemons
 Summary: The talloc library
 License: LGPLv3+
-URL: http://talloc.samba.org/
-Source: http://samba.org/ftp/talloc/talloc-%{version}.tar.gz
-BuildRoot: %(mktemp -ud %{_tmppath}/%{name}-%{version}-%{release}-XXXXXX)
+URL: https://talloc.samba.org/
+Source: https://www.samba.org/ftp/talloc/talloc-%{version}.tar.gz
 
-BuildRequires: autoconf
 BuildRequires: libxslt
 BuildRequires: docbook-style-xsl
 BuildRequires: python2-devel
@@ -100,7 +98,6 @@ make %{?_smp_mflags} V=1
 doxygen doxy.config
 
 %install
-rm -rf $RPM_BUILD_ROOT
 
 make install DESTDIR=$RPM_BUILD_ROOT
 
@@ -114,9 +111,6 @@ rm -f $RPM_BUILD_ROOT/usr/share/swig/*/talloc.i
 # Install API docs
 cp -a doc/man/* $RPM_BUILD_ROOT/%{_mandir}
 
-%clean
-rm -rf $RPM_BUILD_ROOT
-
 %files
 %defattr(-,root,root,-)
 %{_libdir}/libtalloc.so.*