Add staging libraries directories to -L in external case

In order to solve issues of libtool trying to link target components
against host libraries, it seems that specifying -L$(STAGING_DIR)/lib
and -L$(STAGING_DIR)/usr/lib works.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/Makefile.in

@@ -98,6 +98,7 @@ else ifeq ($(BR2_TOOLCHAIN_EXTERNAL),y)
 TARGET_CFLAGS+=--sysroot $(STAGING_DIR)/
 TARGET_CXXFLAGS=$(TARGET_CFLAGS)
 TARGET_LDFLAGS=--sysroot $(STAGING_DIR)/
+TARGET_LDFLAGS+=-L$(STAGING_DIR)/lib -L$(STAGING_DIR)/usr/lib
 endif
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