Fix compiler warning: conditional expression is constant

Fix compiler warning: local variable may be used without having been initialized.

Fix compiler warnings: conversion from 'const int ' to 'unsigned char ', possible loss of data

Fix compiler warning: variable was set but never used

Simplify preprocessor symbol checking

slightly while editing

Conroy's fix to make the code match with the RTP documentation regarding
writing out the whole header. The docs say it writes the whole header,
but the code (before this patch) did not write out the leading $.

simply check for CURLM_CALL_MULTI_PERFORM internally. This has the added
benefit that this goes in line with my long-term wishes to get rid of the
CURLM_CALL_MULTI_PERFORM all together from the public API.

Make Curl_pop3_write() additionally truncate trailing POP3_EOB from received
string buffer, otherwise Curl_client_write() call with zero size would write
to the end of string buffer including matched POP3_EOB.

WIN32 fix, _beginthreadex() may return either 0 or -1L upon failure

fix errno usage for WIN32 builds

RTSP followup fix. Both the pipelined and non-pipelined case need to
check for (excess > 0 && !k->ignorebody).

fix printf-style format strings

fix printf-style format strings

Chris Conroy's RTSP followup fixes

fix compiler warning

  proxy that cannot be resolved when using c-ares. This matches the behaviour
  when not using c-ares.

fix compiler warning

HAVE_GETADDRINFO_THREADSAFE definition for non-configure win32 builds

add inclusion of curl_memory.h

adjust preprocessor symbol definition check relative to resolver specialty

from hostip.h to setup.h in order to allow proper inclusion in any file.

This represents no functional change at all in which resolver is used,
everything still works as usual, internally and externally there is no
difference in behavior.

s/RTPDATA/INTERLEAVEDATA/

removal of Curl_addrinfo_copy(), Curl_addrinfo6_callback(), and
Curl_addrinfo4_callback()