Extract a LICENSE file from arpwatch.c’s comment header

We have emailed upstream requesting a proper license file.

arpwatch.spec

@@ -102,6 +102,11 @@ sed -r -i 's|/usr/local/arpwatch|%{pkgstatedir}|g' *.8.in *.sh.in *.sh
 # Fix Python interpreter path (but note that this script is not installed)
 sed -r -i 's|/usr/local/bin/python|%{python3}|g' update-ethercodes.sh.in
 
+# Emailed upstream requesting a separate LICENSE/COPYING file 2022-07-30.
+# For now, we extract it from the main source file’s “header” comment.
+awk '/^ \* / { print substr($0, 4); } /^ \*\// { exit }' arpwatch.c |
+  tee LICENSE
+
 
 %build
 %configure --with-sendmail=/usr/sbin/sendmail PYTHON=%{python3}
@@ -196,6 +201,7 @@ exit 0
 
 
 %files
+%license LICENSE
 %doc README
 %doc CHANGES
 %doc arpfetch