SF #1685563, MSVCCompiler creates redundant and long PATH strings

If MSVCCompiler.initialize() was called multiple times, the path
would get duplicated.  On Windows, this is a problem because the
path is limited to 4k.  There's no benefit in adding a path multiple
times, so prevent that from occuring.  We also normalize the path
before checking for duplicates so things like /a and /a/ won't both
be stored.

since the 2.5.0 release.

Backport of r54615.

returned by python-config if Python was built with --enable-shared
because that prevented the shared library from being used.
  (backport from rev. 54634)

Fix SF #1688393, sock.recvfrom(-24) crashes

Also fix some method names that were copied incorrectly (trunk fixed).

the C lib's clock() is used, but it must be divided by CLOCKS_PER_SEC
as for the POSIX implementation (thanks to #pypy).
 (backport from rev. 54606)

Python 2.5 added support for explicit relative import statements and
yield expressions, which were missing in the manual.
Also fix grammar productions that used the names from the Grammar file,
markup that broke the generated grammar.txt, and wrap some lines that
broke the pdf output.
 (backport from rev. 54559)

overflows the valid Py_ssize_t range.  Check return values of
PyMem_Malloc.

Backported from trunk.

question (well, two months too late).

The code in this patch leaves no way to give up the ownership of a
BSTR instance.

 (backport from rev. 54524)

now be unpickled.
 (backport form rev. 54492)

given to get(). It also detects when you use '&' as the last argument
and creates a BackgroundBrowser then.
 (backport -- this is a regression from 2.4 and therefore backported)

 (backport from rev. 54483)

masked by a generic one with the message "unpack non-sequence".
 (backport from rev. 54480)

Extend work on rev 52962 and 53830 eliminating redundant PyObject_Hash() calls and fixing set/dict interoperability.

 (backport from rev. 54409)

Backported from r54404.

the implementation for __reduce__ and __reduce_ex__ into two separate
functions. Fixes bug #931877.
 (backport from rev. 54397)

initialization failed.
 (backport from rev. 54394)

thread lib doc.
 (backport from rev. 54392)

name. Remove a reference leak that happened if the name could not be
converted to string.
 (backport from rev. 54378)

AttributeError instead of an IOError when the server's response didn't
contain a valid HTTP status line.
 (backport from rev. 54376)

covers everything now that Mac OS 9 isn't a popular issue.

2047-like headers where there is no whitespace between encoded words.  This
fix changes the matching regexp to include a trailing lookahead assertion that
the closing ?= must be followed by whitespace, newline, or end-of-string.
This also changes the regexp to add the MULTILINE flag.

 (backport from rev. 54365)