contrib/rpm: explicitly enable/disable bluetooth support

The bluetooth plugin (with BlueZ5/NAP support) always gets
build, but DUN support requires a library.

When enabling build of the bluetooth subpackage, then always
enable DUN support. And enable it explicitly, especially meson
would not autodetect support and disable it by default.

contrib/fedora/rpm/NetworkManager.spec

@@ -550,6 +550,11 @@ NetworkManager in cloud setups. Currently only EC2 is supported.
 %else
 	-Diwd=false \
 %endif
+%if %{with bluetooth}
+	-Dbluez5_dun=true \
+%else
+	-Dbluez5_dun=false \
+%endif
 %if %{with nmtui}
 	-Dnmtui=true \
 %else
@@ -676,6 +681,11 @@ intltoolize --automake --copy --force
 %else
 	--with-iwd=no \
 %endif
+%if %{with bluetooth}
+	--enable-bluez5-dun=yes \
+%else
+	--enable-bluez5-dun=no \
+%endif
 %if %{with nmtui}
 	--with-nmtui=yes \
 %else