Closes #1529

Closes #1530

... the torture ones are commented out only because they are slooooow.

Closes #1528

... and update the certinfo.c example accordingly.

Fixes https://github.com/curl/curl/issues/846

... so that they get the required "struct curl_tlssessioninfo **"
arguments.

Fixes #1524

Otherwise, they are removed in the final configure file.
Also changed sed to "$SED" like in most other calls in this file.

"clang -dumpversion" always returns "4.2.1", the GCC version that clang
was initially compatible to. Use "clang -v" instead, which returns the
actual clang version.

Fixes https://github.com/curl/curl/issues/1522
Closes https://github.com/curl/curl/pull/1523

... since closesocket is a function in WinSock.

Reported-by: Marcel Raad
Bug: https://github.com/curl/curl/commit/55fcb8485914700132fd1854c9509b66c955efbe#co
mmitcomment-22347818

Use CURLMcode for variable 'res' and cast to int where necessary
instead of the other way around. Other tests do the same.

This fixes the following clang warning:
lib583.c:68:15: warning: cast from function call of type 'CURLMcode' to
non-matching type 'int' [-Wbad-function-cast]

Reported-by: Gisle Vanem

clang 2.9+ supports -Wshift-sign-overflow, which warns about undefined
behavior on signed left shifts when shifting by too many places.

Ref: https://github.com/curl/curl/issues/1516
Closes https://github.com/curl/curl/pull/1517

wolfSSL configure script relevant changes from 3.10 to 3.11:

- Async threading support added; disabled by default without async
  crypto, which continues to be disabled by default.

wolfSSL configure script relevant changes from 3.11 to 3.11.1 (beta):

- TLS 1.3 beta support added; disabled by default.

For experimenting I put in a comment block the defines needed to enable
TLS 1.3 support (ie the equivalent of --enable-tls13).

Fixes #1208

... with a strlen() if no size was set, and do this in the pretransfer
function so that the info is set early. Otherwise, the default strlen()
done on the POSTFIELDS data never sets state.infilesize.

Reported-by: Vincas Razma
Bug: #1294

- Test curl_msnprintf negative int width arg using INT_MIN instead of
  1 << 31 which is undefined behavior.

Closes https://github.com/curl/curl/issues/1516

vtls/mbedtls.c:804:69: warning: declaration of 'entropy' shadows a global declaration [-Wshadow]
 CURLcode Curl_mbedtls_random(struct Curl_easy *data, unsigned char *entropy,
                                                                     ^~~~~~~

This hasn't been used in over a decade. <precheck> can still be used to
run commands before the main test.

Closes #1509

follow-up to f31760e6

Reported-by: Michael Kaufmann
Bug: https://github.com/curl/curl/pull/1495#issuecomment-303982793

Fix bugs and compiler warnings on systems with 32-bit long and
64-bit time_t.

Reviewed-by: Daniel Stenberg

Closes #1499

This is contained in -Wextra with GCC 7.

Closes #1321