https://github.com/westes/flex/commit/24e73c4446841eda8d4ea01298e887059e8c1472

Bug: https://bugs.gentoo.org/625508

--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -79,6 +79,8 @@ COMMON_SOURCES = \
 
 LDADD = $(LIBOBJS) @LIBINTL@
 
+$(LIBOBJS): $(LIBOBJDIR)$(am__dirstamp)
+
 include_HEADERS = \
 	FlexLexer.h
 
--- a/src/Makefile.in
+++ b/src/Makefile.in
@@ -1688,6 +1688,8 @@ uninstall-am: uninstall-binPROGRAMS uninstall-includeHEADERS \
 @CROSS_TRUE@$(stage1flex_OBJECTS): CPPFLAGS=$(CPPFLAGS_FOR_BUILD)
 @CROSS_TRUE@$(stage1flex_OBJECTS): LDFLAGS=$(LDFLAGS_FOR_BUILD)
 
+$(LIBOBJS): $(LIBOBJDIR)$(am__dirstamp)
+
 skel.c: flex.skl mkskel.sh flexint.h tables_shared.h tables_shared.c
 	$(SHELL) $(srcdir)/mkskel.sh $(srcdir) $(m4) $(VERSION) > $@.tmp
 	mv $@.tmp $@