the specfile already requires pam, add explicit requirement

git-svn-id: https://xpra.org/svn/Xpra/trunk@12749 3bb7dfac-3a0b-4e04-842a-767bc560f471

rpmbuild/xpra.spec

@@ -188,6 +188,7 @@ BuildRequires: libXdamage-devel
 BuildRequires: libXrandr-devel
 BuildRequires: libXext-devel
 BuildRequires: %{libvpx}-devel
+BuildRequires: pam-devel
 %if 0%{?fedora}
 BuildRequires: libwebp-devel
 BuildRequires: libyuv-devel