package/flac: enable building of libFLAC++

Besides libFLAC, also build libFLAC++ when C++ support is enabled.

Signed-off-by: Jörg Krause <joerg.krause@embedded.rocks>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

package/flac/flac.mk

@@ -17,7 +17,7 @@ FLAC_CPE_ID_VENDOR = flac_project
 FLAC_AUTORECONF = YES
 
 FLAC_CONF_OPTS = \
-	--disable-cpplibs \
+	$(if $(BR2_INSTALL_LIBSTDCPP),--enable-cpplibs,--disable-cpplibs) \
 	--disable-xmms-plugin \
 	--disable-altivec