Removed case clause for length = 0 for both HTTP1.0 and HTTP1.1
Fix http_request:http_headers/1 to send content-length when length is zero

In R16B01, the http_request:http_headers/1 function removes the content-length
field from the HTTP headers if the content length is zero. This results in
some (perhaps many) HTTP servers rejecting POSTs and PUTs without data with
a 411 status word. From RFC2616, section 14.13: "Any Content-Length greater than
or EQUAL to zero is a valid value".
Merge branch 'fredrik/inets/httpc_length_zero' into maint

* fredrik/inets/httpc_length_zero:
  Removed case clause for length = 0 for both HTTP1.0 and HTTP1.1
Added guard for invalid field and values in headers
Merge branch 'cm/bug-http-content-length-zero/OTP-10934' into maint

* cm/bug-http-content-length-zero/OTP-10934:
  Fix http_request:http_headers/1 to send content-length when length is zero
inets httpc: Revert incorrect commit regarding cookie handling.
inets: stop block timer with the right arguments
Convert XML files to UTF-8, where needed
Convert XML files to UTF-8
ssl, public_key & inets: Remove use of deprecated crypto functions from
test code
Fix {stream, {self, once}} in httpc

Previously the only difference between {stream, self} and {stream,
{self, once}} was an extra Pid in the stream_start message due to a
bug in httpc_handler. It was immediately sending a bunch of messages
till the end instead of waiting for httpc:stream_next/1 being called.
Remove http_chunk:decode/4 as it is no longer used

http_chunk:decode/4, the side-effecting chunk decoder, was only used
by httpc_handler:handle_http_body/2 but now it's completely unused.
crypto,ssh, netconf, inets: binary_to_integer -> bytes_to_integer
crypto, public_key & ssl: Make more functions accept integer keys
Merge remote-tracking branch 'upstream/maint'

Conflicts:
	bootstrap/lib/stdlib/ebin/beam_lib.beam
	lib/public_key/test/erl_make_certs.erl
Merge branch 'md/httpc-stream-once-fix/OTP-11122' into maint

* md/httpc-stream-once-fix/OTP-11122:
  Remove http_chunk:decode/4 as it is no longer used
  Fix {stream, {self, once}} in httpc
Merge branch 'maint'