Avoid casting away low-level const.

... to really make sure the boundary fits in the target buffer.

Fixes unused parameter 'buflen' warning.

Reported-by: Michael Kaufmann
Bug: https://github.com/curl/curl/pull/1468#issuecomment-300078754

... using the docs/cmdline-opts/gen.pl script, so that we get all the
command line option documentation from the same source.

The generation of the list has to be done manually and pasted into the
source code.

Closes #1465

When the random seed is purposely made predictable for testing purposes
by using the CURL_ENTROPY environment variable, process that data in an
endian agnostic way so the the initial random seed is the same
regardless of endianness.

- Change Curl_rand to write to a char array instead of int array.

- Add Curl_rand_hex to write random hex characters to a buffer.

Fixes #1315
Closes #1468

Co-authored-by: Daniel Stenberg
Reported-by: Michael Kaufmann

Otherwise, subsequent uses of stunnel overwrite the configuration file
of previous invocations so they can no longer be inspected.

Commit 481e0de0 changed the variable
type from int to size_t, so don't cast the result of strlen to int
anymore.

alarm's argument is unsigned.

long is 32 bits while size_t is 64 bits on MinGW-w64, so
typecheck-gcc.h complains when using size_t for a long option.
Also, curl_socket_t is unsigned long long rather than int.

... to also make it update when we remove files, like we did for
--environment in commit a8e388dd.

Avoids narrowing conversion warnings because rlim_t is usually
unsigned long.

Closes https://github.com/curl/curl/pull/1469

The first argument to select is an int, while curl_socket_t is
unsigned long long when using WinSock. It's ignored anyway [1].

[1] https://msdn.microsoft.com/en-us/library/windows/desktop/ms740141.aspx

Don't convert string literal to char * before assigning it to
const char *.

Don't do anything in this file if CURLRES_THREADED is not defined.

The cases this warns about are handled elsewhere, so just use an
intermediate variable to silence the warning.

Apparently, /usr/bin/m4 ignores the --version parameter and waits for
input from stdin.

Fixes #1471

...to render properly nroff.

... and USE_ENVIRONMENT and --environment. It was once added for RISC OS
support and its platform specific behavior has been annoying ever
since. Added in commit c3c8bbd3, mostly unchanged since
then. Most probably not actually used for years.

Closes #1463

Also, document that numbered datacheck sections are possible.

Avoid casting string literals to non-const char *.

calloc and ai_addrlen expect different (usually unsigned) types.

Suggested-by: Dan Fandrich

... instead of numerical order.

Closes #1466

assign string literals to const char * instead of char * in order to
avoid a lot of these warnings:
cast from 'const char *' to 'char *' drops const qualifier
[-Wcast-qual]

Windows does not allow setting the locale with environment variables (as
the test attempted to do), so the test failed when run with a user
locale that has a comma as radixchar. Changed the test to call
setlocale() explicitly to ensure that a known working locale is set even
on Windows.

SEND_QUAL_ARG2 had to be set, but was never used. Use it in swrite to
avoid warnings about casting away low-level const.

Closes https://github.com/curl/curl/pull/1464