import-lx_emul_common.inc: don't use 'nm -U'

The option is used during the generation of initcall_table.c.
However, it happens to strip the first argument following the option.
The long option --defined-only works as expected.

Issue #5155

repos/dde_linux/lib/import/import-lx_emul_common.inc

@@ -262,7 +262,7 @@ endef
 WAIT_FOR_OBJECTS = $(addsuffix .o,$(basename $(filter-out initcall_table.c,$(SRC_C))))
 
 # retrieve 'initptr_*' using nm from object files
-INITCALLS = $(sort $(shell $(NM) -U $(WAIT_FOR_OBJECTS) |\
+INITCALLS = $(sort $(shell $(NM) --defined-only $(WAIT_FOR_OBJECTS) |\
               grep "__initptr" |\
               awk '{print $$3}'))