treewide: configureFlags is a flat list

pkgs/servers/http/nginx/generic.nix

@@ -53,15 +53,15 @@ stdenv.mkDerivation {
     "--with-http_stub_status_module"
     "--with-threads"
     "--with-pcre-jit"
-  ] ++ optional withDebug [
+  ] ++ optionals withDebug [
     "--with-debug"
-  ] ++ optional withStream [
+  ] ++ optionals withStream [
     "--with-stream"
     "--with-stream_geoip_module"
     "--with-stream_realip_module"
     "--with-stream_ssl_module"
     "--with-stream_ssl_preread_module"
-  ] ++ optional withMail [
+  ] ++ optionals withMail [
     "--with-mail"
     "--with-mail_ssl_module"
   ] ++ optional (perl != null) [

pkgs/servers/http/tengine/default.nix

@@ -53,23 +53,23 @@ stdenv.mkDerivation rec {
     "--with-poll_module"
     "--with-google_perftools_module"
     "--with-jemalloc"
-  ] ++ optional withDebug [
+  ] ++ optionals withDebug [
     "--with-debug"
-  ] ++ optional withMail [
+  ] ++ optionals withMail [
     "--with-mail"
     "--with-mail_ssl_module"
-  ] ++ optional (!withMail) [
+  ] ++ optionals (!withMail) [
     "--without-mail_pop3_module"
     "--without-mail_imap_module"
     "--without-mail_smtp_module"
-  ] ++ optional withStream [
+  ] ++ optionals withStream [
     "--with-stream"
     "--with-stream_ssl_module"
     "--with-stream_realip_module"
     "--with-stream_geoip_module"
     "--with-stream_ssl_preread_module"
     "--with-stream_sni"
-  ] ++ optional (!withStream) [
+  ] ++ optionals (!withStream) [
     "--without-stream_limit_conn_module"
     "--without-stream_access_module"
     "--without-stream_geo_module"

pkgs/servers/http/unit/default.nix

@@ -47,9 +47,9 @@ stdenv.mkDerivation rec {
     "--pid=/run/unit/unit.pid"
     "--user=unit"
     "--group=unit"
-  ] ++ optional withSSL     [ "--openssl" ]
-    ++ optional (!withIPv6) [ "--no-ipv6" ]
-    ++ optional withDebug   [ "--debug" ];
+  ] ++ optional withSSL     "--openssl"
+    ++ optional (!withIPv6) "--no-ipv6"
+    ++ optional withDebug   "--debug";
 
   postConfigure = ''
     ${optionalString withPython2    "./configure python --module=python2  --config=${python2}/bin/python2-config  --lib-path=${python2}/lib"}