When switching to HTTP because a HTTP proxy is being used, the existing
handler is now checked if it already is "compatible". This allows the https
handler remain while other non-http handlers will be redirected.

Bug: http://curl.haxx.se/mail/lib-2011-05/0214.html
Reported by: Jerome Robert

Fix compiler warning: variable was set but never used

Fix compiler warning: clobber ignored

Fix compiler warning: variable was set but never used

Fix compiler warning: clobber ignored

Enclose header file in an inclusion guard

Fix compiler warning: expression has no effect

Fix compiler warning: `keycheck' might be used uninitialized in this function.
Fix compiler warning: `keybit' might be used uninitialized in this function.

Fix variable declaration placement

Fix missing semicolon

Fix compiler warning: expression has no effect

Fix OOM handling

Fix compiler warning: expression has no effect

Fix compiler warning: unused variable 'data'

Fix compiler warning: enumerated type mixed with another type

Fix compiler warning: enumerated type mixed with another type

Fix compiler warning: enumerated type mixed with another type

Fix compiler warning: enumerated type mixed with another type

Fix compiler warning: empty body in an if-statement

Get cyassl's NO_FILESYSTEM to work with libcurl. Otherwise I'd get linker
errors for the missing "SSL_CTX_load_verify_locations" functions.

Fix linkage on c-ares enabled Windows static builds

Fix the return type of the callback to match close() and make use of it.

Introduced the initial setup to allow closesocket callbacks by making
sure sclose() is only ever called from one place in the libcurl source
and still run all test cases fine.

Commit cbf4961b garbled the timeout handling while doing SSL
handshaking (in an attempt at fixing another bug). This puts sanity
back.

Bug: http://curl.haxx.se/mail/lib-2011-05/0167.html
Reported by: Ethan Glasser Camp

The protocol handler's flags field now can set that the protocol
requires a password, so that the set_userpass function doesn't have to
have the specific knowledge of which protocols that do.

Made several functions static

Made one function defined to nothing when RTSP is disabled to avoid
the #ifdefs in code.

Removed explicit rtsp.h includes

Add a 'readwrite' function to the protocol handler struct and use that
for the extra readwrite functionality RTSP needs.

Code cleanup to check less for protocols and more for the specific
relevant feature. Like if SSL is required.

No need to check for HTTP as this is now a HTTP-specific function

make it static, remove Curl_ prefix

Also, convert the BANPROXY flag into NONETWORK for the protocols
(file:// only atm) that don't work over networks.

Using 'socks5h' as proxy protocol will make it a
CURLPROXY_SOCKS5_HOSTNAME proxy which is SOCKS5 and asking the proxy to
resolve host names. I found no "standard" protocol name for this.

closepolicy has been deprecated and unused for years

Introduce an INIT state for the SSH state machine and set libssh2
non-blocking in that so that it is set properly before
libssh2_session_startup() is called.

Bug: http://curl.haxx.se/mail/archive-2011-05/0001.html

When checking for connections that are bound to a particular device we
must make sure we don't compare with a NULL pointer.