extract-copyright-comments: Fix detection of "**/"

For example, in networking/nslookup.c:

    /****** A version from LEDE / OpenWRT ******/

1 files changed, 7 insertions, 3 deletions

diff --git a/extract-copyright-comments b/extract-copyright-comments
index 6b603b6..87d0d3b 100755
--- a/extract-copyright-comments
+++ b/extract-copyright-comments
@@ -67,23 +67,27 @@ extract_cxx_comment()
 extract_c_comment()
 {
 	local comment='/*'
+	local asterisk=false
 
 	while :; do
 		getc
 		case "${c}" in
 			'*')
+				asterisk=true
 				comment="${comment}${c}"
-				getc
+				;;
+			'/')
 				comment="${comment}${c}"
-				case "${c}" in '/')
+				if ${asterisk}; then
 					break
-				esac
+				fi
 				;;
 			'')
 				printf '\tError: Unterminated C comment\n' 1>&2
 				return 1
 				;;
 			*)
+				asterisk=false
 				comment="${comment}${c}"
 				;;
 		esac