libmpdclient: fix install

By default, meson adds the build machine architecture for installation,
see: https://github.com/mesonbuild/meson/issues/2535
Use --libdir to override this default behavior

Fixes:
 - http://autobuild.buildroot.net/results/aec/aec9f3de545a832b66cd00c217fbaa99246e1715
 - http://autobuild.buildroot.net/results/07a/07adcba71106a2dca963e4071f4673791b41a603
 - http://autobuild.buildroot.net/results/a27/a272a8e521863374901a5e3c0fb9da0b8daa4076

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/libmpdclient/libmpdclient.mk

@@ -15,6 +15,7 @@ LIBMPDCLIENT_DEPENDENCIES = host-meson
 
 LIBMPDCLIENT_CONF_OPTS += \
 	--prefix=/usr \
+	--libdir=/usr/lib \
 	--buildtype $(if $(BR2_ENABLE_DEBUG),debug,release) \
 	--cross-file $(HOST_DIR)/etc/meson/cross-compilation.conf