wpa_supplicant: adjust make environment for pkg-config call

In case that wpa_supplicant is configured with DBus interface,
it calls pkg-config to find the dbus headers and libraries.
Adjust the make environment so that it will use the right
pkg-config search paths.

Signed-off-by: Sven Neumann <s.neumann@raumfeld.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

package/wpa_supplicant/wpa_supplicant.mk

@@ -19,7 +19,10 @@ ifeq ($(BR2_PACKAGE_WPA_SUPPLICANT_OPENSSL),y)
 	WPA_SUPPLICANT_DEPENDENCIES += openssl
 endif
 ifeq ($(BR2_PACKAGE_DBUS),y)
-	WPA_SUPPLICANT_DEPENDENCIES += dbus
+	WPA_SUPPLICANT_DEPENDENCIES += host-pkgconfig dbus
+	WPA_SUPPLICANT_MAKE_ENV = \
+		PKG_CONFIG_SYSROOT_DIR="$(STAGING_DIR)"	\
+		PKG_CONFIG_PATH="$(STAGING_DIR)/usr/lib/pkgconfig"
 endif
 
 $(eval $(call AUTOTARGETS,package,wpa_supplicant))