REUSE: move copyright headers to .checksrc

To make it simpler to move them around, create and delete them without
syncing with `REUSE.toml`.

Also:
- checksrc: allow empty lines in `.checksrc`.
- comment on why curl printfs are disallowed in examples.

Closes #19024

REUSE.toml

@@ -39,11 +39,6 @@ path = [
   "tests/certs/**",
   "tests/data/test**",
   "tests/valgrind.supp",
-  # checksrc control files
-  "docs/examples/.checksrc",
-  "scripts/.checksrc",
-  "src/.checksrc",
-  "tests/server/.checksrc",
 ]
 SPDX-FileCopyrightText = "Daniel Stenberg, <daniel@haxx.se>, et al."
 SPDX-License-Identifier = "curl"

docs/examples/.checksrc

@@ -1,3 +1,7 @@
+# Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
+#
+# SPDX-License-Identifier: curl
+
 allowfunc fclose
 allowfunc fdopen
 allowfunc fopen
@@ -11,6 +15,8 @@ allowfunc socket
 allowfunc sscanf
 allowfunc strerror
 allowfunc vsnprintf
+
+# Use of curl printf functions is discouraged
 banfunc curl_maprintf
 banfunc curl_mfprintf
 banfunc curl_mprintf

scripts/.checksrc

@@ -1 +1,5 @@
+# Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
+#
+# SPDX-License-Identifier: curl
+
 allowfunc printf

scripts/checksrc.pl

@@ -202,6 +202,10 @@ sub readlocalfile {
         if(/^\s*(#.*)/) {
             next;
         }
+        # Skip empty lines
+        elsif($_ eq '') {
+            next;
+        }
         elsif(/^enable ([A-Z]+)$/) {
             if(!defined($warnings_extended{$1})) {
                 print STDERR "invalid warning specified in .checksrc: \"$1\"\n";

src/.checksrc

@@ -1 +1,5 @@
+# Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
+#
+# SPDX-License-Identifier: curl
+
 enable STDERR

tests/server/.checksrc

@@ -1,3 +1,7 @@
+# Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
+#
+# SPDX-License-Identifier: curl
+
 allowfunc accept
 allowfunc fclose
 allowfunc fopen