curl.rc: switch out the copyright symbol for plain ASCII

.. like we already do for libcurl.rc.

libcurl.rc copyright symbol used to cause a "non-ascii 8-bit codepoint"
warning so it was switched to ascii.

Ref: curl@1ca62bb5#commitcomment-133474972

Suggested-by: Robert Southee

Closes curl#12403

src/curl.rc

@@ -53,7 +53,7 @@ BEGIN
  VALUE "OriginalFilename", "curl.exe\0"
  VALUE "ProductName", "The curl executable\0"
  VALUE "ProductVersion", CURL_VERSION "\0"
- VALUE "LegalCopyright", "\xa9 " CURL_COPYRIGHT "\0" /* a9: Copyright symbol */
+ VALUE "LegalCopyright", "Copyright (C) " CURL_COPYRIGHT "\0"
  VALUE "License", "https://curl.se/docs/copyright.html\0"
  END
  END