NSS_InitContext() was introduced in NSS 3.12.5 and helps to prevent
collisions on NSS initialization/shutdown with other libraries.

Bug: https://bugzilla.redhat.com/738456

This bumps the minimal supported version of NSS to 3.12.x.

Allow repeatable file name length reduction on file names with underscore or
dash characters. This is done in order to better support libcurl's existing
source file names and allow OS/400 package to build out of the box again.

configure script now provides conditional definitions for Makefile.am
that result in CURL_HIDDEN_SYMBOLS being defined by resulting makefiles
when appropriate.

Additionally, configure script option for symbol hiding control is now
named --enable-symbol-hiding --disable-symbol-hiding. While still valid,
old option name --enable-hidden-symbols --disable-hidden-symbols will
be deprecated in some future release.

Undefining CURL_HIDDEN_SYMBOLS in source files isn't the proper fix.

Undefine CURL_HIDDEN_SYMBOLS libcurl private preprocessor macro that might
leak from lib/setup.h into source files where this should not be defined.

Undefine CURL_HIDDEN_SYMBOLS libcurl private preprocessor macro that might
leak from lib/setup.h into source files where this should not be defined.

lib/config-win32.h no longer copied to src/config-win32.h

BUILDING_LIBCURL and CURL_STATICLIB are no longer defined in curl_config.h,
configure will generate appropriate conditionals so that mentioned symbols
get defined and used in Makefiles at compilation time

amigaos.[ch] now integrates nicely with any libcurl build

Configuration files such as curl_config.h and all config-*.h no longer exist
nor are generated/copied into 'src' directory, now these only exist in 'lib'
directory from where curl tool sources uses them.

Additionally old src/setup.h has been refactored into src/tool_setup.h which
now pulls lib/setup.h

The possibility of a makefile needing an include path adjustment exists.

When a server certificate matches one in the given CRL file, the code
now returns CURLE_SSL_CACERT as test case 313 expects and verifies.

Previously it would say PolarSSL only, now it says PolarSSL/1.1.0 in the
same style other libs and components do.

As it turns out, some people do want that after all.

Verify that cookies are sent back even after a 407 response has been
received

This reverts commit f7e2ab62.

This change caused fetching of the certificates to become unreliable.

Bug: http://curl.haxx.se/mail/lib-2012-03/0238.html
Reported by: Tim Heckman

Commit 97b66ebe was copying a smaller buffer, thus duplicating the last
character.

... as it seems to hard for some people

Don't set the "has_openssl" variable if yassl or polarssl is found as
they will simply not work as 100% drop-in replacements for some of the
stuff the "OpenSSL" feature is used for.

I spotted this problem when doing test runs with PolarSSL builds.