The _FORM_DEBUG-enabled code is not valid anymore:
 
_ "value[56]length" measure wrong strings
_ "size" must be typed "curl_off_t" and associated print code updated
accordingly
_ Typo "PTRCOTNENTS" in code and comment.

The attached patch fixes all of these. In addition, it defines a full
standard prototype for the main() function.

Please note that comments are not accurate anymore:

_ The compilation module list (line 27) is not sufficient (missing
externals at load time).
_ Automatic "Content-Type" is not "text/plain", but
"application/octet-stream"

These commenting issues are NOT adjusted by the patch.