package/erlang-p1-xmpp: add missing dependency on C++ from erlang-p1-stringprep

This package selects erlang-p1-stringprep, which depends on
BR2_INSTALL_LIBSTDCPP. Thus, it should also depend on this item.

Fixes:

  http://autobuild.buildroot.net/results/fe76971fead52acdd64612161e92a48a4ad36572/

Signed-off-by: Johan Oudinet <johan.oudinet@green-communications.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/erlang-p1-xmpp/Config.in

@@ -1,5 +1,9 @@
+comment "erlang-p1-xmpp needs a toolchain w/ C++"
+	depends on !BR2_INSTALL_LIBSTDCPP
+
 config BR2_PACKAGE_ERLANG_P1_XMPP
 	bool "erlang-p1-xmpp"
+	depends on BR2_INSTALL_LIBSTDCPP # erlang-p1-stringprep
 	select BR2_PACKAGE_ERLANG_P1_XML
 	select BR2_PACKAGE_ERLANG_P1_STRINGPREP
 	help