Merge 3.4's PCbuild/readme.txt update.

All the new information in 3.4's readme.txt was already here, but the
wrong name was used to refer to the script.  Also reworded the sentence.

diff --cc PCbuild/readme.txt
index 26739a3f5f38c9b7543791425b357e2463751927,c27af9989b723a4b793bd516e84805c64eaf3f32..26622f55e36e688ec244da3dbf17b410f763d3fb
--- 1/PCbuild/readme.txt
--- 2/PCbuild/readme.txt
+++ b/PCbuild/readme.txt
@@@ -208,28 -182,37 +208,29 @@@ _ss
      to be somewhere on your PATH.  More recent versions of OpenSSL may\r
      need a later version of NASM. If OpenSSL's self tests don't pass,\r
      you should first try to update NASM and do a full rebuild of\r
-     OpenSSL.  get_externals.py also downloads a snapshot of NASM, and the\r
-     libeay and ssleay sub-projects use that version of nasm.exe.\r
+     OpenSSL.  If you use the PCbuild\get_externals.bat method\r
+     for getting sources, it also downloads a version of NASM which the\r
 -    ssl build script will add to PATH.\r
++    libeay/ssleay sub-projects use.\r
 +\r
 +    The libeay/ssleay sub-projects expect your OpenSSL sources to have\r
 +    already been configured and be ready to build.  If you get your sources\r
 +    from svn.python.org as suggested in the "Getting External Sources"\r
 +    section below, the OpenSSL source will already be ready to go.  If\r
 +    you want to build a different version, you will need to run\r
  \r
 -    If you like to use the official sources instead of the files from\r
 -    python.org's subversion repository, Perl is required to build the\r
 -    necessary makefiles and assembly files.  ActivePerl is available\r
 -    from\r
 +       PCbuild\prepare_ssl.py path\to\openssl-source-dir\r
 +\r
 +    That script will prepare your OpenSSL sources in the same way that\r
 +    those available on svn.python.org have been prepared.  Note that\r
 +    Perl must be installed and available on your PATH to configure\r
 +    OpenSSL.  ActivePerl is recommended and is available from\r
          http://www.activestate.com/activeperl/\r
 -    The svn.python.org version contains pre-built makefiles and assembly\r
 -    files.\r
 -\r
 -    The build process makes sure that no patented algorithms are\r
 -    included.  For now RC5, MDC2 and IDEA are excluded from the build.\r
 -    You may have to manually remove $(OBJ_D)\i_*.obj from ms\nt.mak if\r
 -    using official sources; the svn.python.org-hosted version is already\r
 -    fixed.\r
 -\r
 -    The ssl.vcxproj sub-project simply invokes PCbuild/build_ssl.py,\r
 -    which locates and builds OpenSSL.\r
 -\r
 -    build_ssl.py attempts to catch the most common errors (such as not\r
 -    being able to find OpenSSL sources, or not being able to find a Perl\r
 -    that works with OpenSSL) and give a reasonable error message.  If\r
 -    you have a problem that doesn't seem to be handled correctly (e.g.,\r
 -    you know you have ActivePerl but we can't find it), please take a\r
 -    peek at build_ssl.py and suggest patches.  Note that build_ssl.py\r
 -    should be able to be run directly from the command-line.\r
 -\r
 -    The ssl sub-project does not have the ability to clean the OpenSSL\r
 -    build; if you need to rebuild, you'll have to clean it by hand.\r
 +\r
 +    The libeay and ssleay sub-projects will build the modules of OpenSSL\r
 +    required by _ssl and _hashlib and may need to be manually updated when\r
 +    upgrading to a newer version of OpenSSL or when adding new\r
 +    functionality to _ssl or _hashlib. They will not clean up their output\r
 +    with the normal Clean target; CleanAll should be used instead.\r
  _sqlite3\r
      Wraps SQLite 3.8.3.1, which is itself built by sqlite3.vcxproj\r
      Homepage:\r