guile: fix static-only build

guile uses bdwgc, which is already compiled with GC_NO_DLOPEN in
static-only scenarios. However, the bdwgc headers continue to include
<dlfcn.h> if used with GC_NO_DLOPEN undefined.

Therefore, to make guile link properly in a static-only scenario, we
have to build it with GC_NO_DLOPEN defined.

Fixes:

  http://autobuild.buildroot.net/results/1bf/1bf73dd4c28d6607e8c24d3abf259b8032712a02/

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

package/guile/guile.mk

@@ -28,6 +28,10 @@ GUILE_CFLAGS = \
 	-DHAVE_GC_GET_FREE_SPACE_DIVISOR \
 	-DHAVE_GC_SET_FINALIZE_ON_DEMAND
 
+ifeq ($(BR2_STATIC_LIBS),y)
+GUILE_CFLAGS += -DGC_NO_DLOPEN
+endif
+
 GUILE_CONF_ENV += GUILE_FOR_BUILD=$(HOST_DIR)/usr/bin/guile \
 	CFLAGS="$(TARGET_CFLAGS) $(GUILE_CFLAGS)"