Removed the extraneous "rm -f ... rcx_rules.info" line from the Makefile.

sky130/Makefile.in

diff --git a/sky130/Makefile.in b/sky130/Makefile.in
index 1461b3e..6715ffa 100644
--- a/sky130/Makefile.in
+++ b/sky130/Makefile.in
@@ -939,7 +939,6 @@
 	    rm -f ${OPENLANE_STAGING_$*}/sky130_osu_sc_t18/$$file ; \
 	done
 
-	rm -f ${OPENLANE_STAGING_$*}/rcx_rules.info
 	rm -f ${OPENLANE_STAGING_$*}/rules.openrcx.sky130$*.min.magic
 	rm -f ${OPENLANE_STAGING_$*}/rules.openrcx.sky130$*.nom.magic
 	rm -f ${OPENLANE_STAGING_$*}/rules.openrcx.sky130$*.max.magic