Remove deprecated -undefined dynamic_lookup

Instead, use ${PLUGIN_LDFLAGS_BUNDLE_LOADER} when building a .bundle,
which can then be set to -bundle_loader path_to_executable.

buildsys.mk.in

@@ -296,6 +296,7 @@ ${PLUGIN} ${PLUGIN_NOINST}: ${EXT_DEPS} ${PLUGIN_OBJS}
 	if @LINK_PLUGIN@; then \
 		${LINK_OK}; \
 	else \
+		rm -fr $$out; \
 		${LINK_FAILED}; \
 	fi
 

m4/buildsys.m4

@@ -179,7 +179,7 @@ AC_DEFUN([BUILDSYS_SHARED_LIB], [
 			LIB_SUFFIX='.dylib'
 			LDFLAGS_RPATH='-Wl,-rpath,${libdir}'
 			PLUGIN_CFLAGS='-fPIC -DPIC'
-			PLUGIN_LDFLAGS='-bundle -undefined dynamic_lookup'
+			PLUGIN_LDFLAGS='-bundle ${PLUGIN_LDFLAGS_BUNDLE_LOADER}'
 			PLUGIN_SUFFIX='.bundle'
 			AS_IF([test x"$host_is_ios" = x"yes"], [
 				LINK_PLUGIN='rm -fr $$out && ${MKDIR_P} $$out && ${LD} -o $$out/$${out%${PLUGIN_SUFFIX}} ${PLUGIN_OBJS} ${PLUGIN_OBJS_EXTRA} ${PLUGIN_LDFLAGS} ${LDFLAGS} ${LIBS} && ${CODESIGN} -fs ${CODESIGN_IDENTITY} --timestamp=none $$out'