http: Stop reading after receiving the whole file for non-chunked transfers

Previously this logic was only used if the server didn't
respond with Connection: close, but use it even for that case,
if the server response is non-chunked.

Originally the http code has relied on Connection: close to close
the socket when the file/stream is received - the http protocol
code just kept reading from the socket until the socket was closed.
In f240ed18 we added a check for the file size, because some
http servers didn't respond with Connection: close (and wouldn't
close the socket) even though we requested it, which meant that the
http protocol blocked for a long time at the end of files, waiting
for a socket level timeout.

When reading over tls, trying to read at the end of the connection,
when the peer has closed the connection, can produce spurious (but
harmless) warnings. Therefore always voluntarily stop reading when
the specified file size has been received, if not using a chunked
transfer encoding. (For chunked transfers, we already return 0
as soon as we get the chunk header indicating end of stream.)

Signed-off-by: Martin Storsjö <martin@martin.st>
w32threads: Use newer thread synchronization functions when targeting Vista

When explicitly targeting Vista or newer (which only happens if the
caller explicitly sets _WIN32_WINNT to a high enough value via the
extra cflags option - otherwise configure script sets
-D_WIN32_WINNT=0x0502), we already unconditionally link to the
ConditionVariable functions, since 4622f11f9.

Similarly use the newer -Ex versions of CreateEvent, CreateSemaphore,
InitializeCriticalSection and WaitForSingleObject, that all appeared
in Vista. When building Windows Store applications, the older versions
of these functions aren't available, only the -Ex functions. When
doing such a build, the user can set -D_WIN32_WINNT=0x0600 to
forcibly use the newer functions instead.

Signed-off-by: Martin Storsjö <martin@martin.st>
configure: Check for nanosleep in headers as well, not only in libs

On mingw64 with c++11 support, the link libraries do contain a
nanosleep function, while it isn't exposed via the headers. Using
check_func_headers instead of a plain check_func fixes this
misdetection.

Signed-off-by: Martin Storsjö <martin@martin.st>
doc/filters: correct confusing statements about *showinfo shown values

Fix trac issue #3850.
Merge commit '8bf3bf69ad7333bf0c45f4d2797fc2c61bc8922f'

* commit '8bf3bf69ad7333bf0c45f4d2797fc2c61bc8922f':
  http: Stop reading after receiving the whole file for non-chunked transfers

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit '428b0578c64241fc677fed7083cc8fe65e10f32e'

* commit '428b0578c64241fc677fed7083cc8fe65e10f32e':
  w32threads: Use newer thread synchronization functions when targeting Vista

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit '72199e1041b4052544e181ad90b431ca6704da12'

* commit '72199e1041b4052544e181ad90b431ca6704da12':
  configure: Check for nanosleep in headers as well, not only in libs

See: 223c374a9d977fdfe9af94858693c632f644aac7
Merged-by: Michael Niedermayer <michaelni@gmx.at>
avfilter/dctdnoiz: add slice threading
Changelog: notify about the recent performance boost in dctdnoiz filter
vp9: ignore reference segmentation map if error_resilience flag is set.

Fixes ffvp9_fails_where_libvpx.succeeds.webm from ticket 3849.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>