add multipart/form-data body builder

extend link.mk with BUILD_ENV for compile-time env vars

add link.mk declaring native libs needed by consumers

add examples/post for POSTing a body to a URL - body from argv or stdin (-), sent as application/json - prints response status line, headers, and body

add HTTPS client, parsers, and chunked transfer-coding - Method / Version / Status (is_* predicates, canonical reason phrases) and case-insensitive ordered Headers - parse_request and parse_response_head per RFC 2616 §5/§6, accepting bare LF (§19.3) and obs-fold (§2.2) - response_body_length / request_body_length covering the §4.4 matrix - ChunkedReader / ChunkedWriter per §3.6.1 for SSE-style streaming - RequestBuilder + top-level get/head/post/put/delete/patch/request; send() returns a Response that implements Read, with Host, User-Agent, Connection: close, and Content-Length auto-set - TlsStream wraps libtls and propagates -ltls via #[link] - percent_encode, percent_decode, url_form; RequestBuilder::form - examples/get.rs and 34 inline tests

add examples/ and expose VERSION const Populate VERSION from the HTTP_VERSION environment variable which make already passes to rustc, so downstream crates can print or log the library version without a second source of truth. Add examples/hello.rs, a minimal binary that links against the rlib and prints the version. A generic Makefile pattern rule builds any file under examples/ into build/ex-<name>, driven by the new examples target.

initial import of http, a single-file HTTP library