Revert "Makefile.in: Fix failed build from release archive"

This reverts commit 04c1b0a71a8c08a24a63226cf1d9d968adcb7bb0.

This is part of a move to require Flex 2.5.31 or later and to use
features in those versions of Flex, including %top.
diff --git a/Makefile.in b/Makefile.in
index 70c924b..2e62a8e 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -338,7 +338,6 @@
 	pcap-usb-linux.h \
 	pcap-win32.c \
 	runlex.sh \
-	scanner.c.top \
 	scanner.l \
 	Win32/Include/Gnuc.h \
 	Win32/Include/net/if.h \