telnet: fix macros to allow proper semicolon use

Macros that look like function calls need to be made so that we can use
semicolons properly for indentation and for reducing the risk for
mistakes when using them.
tvdiff_secs(): sub-zero time difference adjustment

Skip a floating point addition operation when integral part of time difference
is zero. This avoids potential floating point addition rounding problems while
preserving decimal part value.
telnet.c: fix MSVC compiler warning
SSLSESSION_SHARED: new macro to check if session is shared

Added convenience macro to use to check if a handle is using a shared
SSL session, and fixed so that Curl_ssl_close_all() doesn't lock when
the session isn't shared.
rectify comment
CyaSSL 2.0+ library initialization adjustment
FTP tests 1206 - 1209: don't expect QUIT

The protocol parts for these tests do not include QUIT simply because
the error is CURLE_OPERATION_TIMEDOUT (28) which is a generic timeout
error without specificly saying for which connection it concerns, and
for timeouts libcurl marks the control channel as "invalid". As this
test case times out for the data connection it could still use the
control channel.
configure: add support for pkg-config detection of libidn
test 1211: FTP test to repeat bug #3429299

"Active FTP hangs if server does not open data connection"

The server first sends a 150 and then when libcurl waits for the data
transfer, the server sends a 425.
configure: fix to make older pkg-config play well

configure.ac:1349: error: possibly undefined macro: PKG_CONFIG_LIBDIR

Obviously this is not a problem with pkg-config 0.26 but older versions
seem to show this.

Fix suggested by: Kamil Dudka
Reported by: Guenter
Bug: http://curl.haxx.se/mail/lib-2011-11/0298.html
test: added POP3 test with dot-prefixed line

Test 815 is disabled for now since libcurl currently doesn't unescape
such lines the way it should. See mail:

http://curl.haxx.se/mail/lib-2011-11/0324.html
POP3: fix end of body detection

Curl_pop3_write() now has a state machine that scans for the end of a
POP3 body so that the CR LF '.' CR LF sequence can come in everything
from one up to five subsequent packets.

Test case 810 is modified to use SLOWDOWN which makes the server pause
between each single byte and thus makes the POP3 body get sent to curl
basically one byte at a time.
ftpserver: output CRLF in logs

Previously the log function would just filter out all CR and LF
occurances from the log to make it more readable. This had the downside
that it made it very hard to see CR LFs when they actually matters.

Now, they're instead converted to "[CR]" and "[LR]" in the log to become
apparent to readers.
POP3: detect when LIST returns no mails

By making sure the function can detect an "end of body" sequence
immediately on the first line, test 811 is now enabled.
configure: avoid usage of macro PKG_CHECK_MODULES

libidn option adjusted in order to use pkg-config info when available
in a similar way as we already do for other libraries.
pop3.c: fix compiler warning
RELEASE-NOTES: synced with 1038d0aa1

5 bugfixes and 1 new contributor
buildconf: fix libtool 1.5.x warnings triggered with autoconf 2.6x or later

Using libtool 1.5.x (x < 26) with autoconf 2.6x or later generates warnings
due to some libtool variables not following naming convention for variables
that will be cached.

This is addressed renaming a couple of variables to make these follow expected
naming convention.
buildconf: follow-up for commit 7e02f7fd
POP3: fixed escaped dot not being striped out

Changed the eob detection to work across the whole of the buffer so that
lines that begin with a dot (which the server will have escaped) are
passed to the client application correctly.