ematch: fix warning about unused input()

Use existing compile flag to indicate that input() is not used
by tc ematch, fixes compiler warning.
diff --git a/tc/Makefile b/tc/Makefile
index 00abb7f..a3d270d 100644
--- a/tc/Makefile
+++ b/tc/Makefile
@@ -89,6 +89,7 @@
 
 YACC := bison
 LEX := flex
+CFLAGS += -DYY_NO_INPUT
 
 MODDESTDIR := $(DESTDIR)$(patsubst /usr%,%,$(LIBDIR))/tc