Support for --with-pydebug builds.

python.jam:

  Support for the specification of "_d" extension suffix.

  In compute-default-paths, fixed the check for residence in
  a "PCBuild.*" directory so we can build against Windows Python built
  in a source distribution.

common.jam:

  Fixed generation of the "y" tag to look for <python-debugging>on
  rather than the whole debug-python build variant.

  Fixed some grammar and spelling.

virtual-target.jam:

  Added the ability to forego the prepending of "." to a
  generated-target-suffix by specifying the suffix enclosed in <...>

libs/python/build/Jamfile.v2:

  #define BOOST_DEBUG_PYTHON when <python-debugging>on


[SVN r37326]

build/Jamfile.v2

@@ -63,10 +63,13 @@ lib boost_python
         # import library, as usage requirements.
         <library>/python//python_for_extensions
       
+        <python-debugging>on:<define>BOOST_DEBUG_PYTHON
+      
     :   # default build
         <link>shared
     :   # usage requirements
         <link>static:<define>BOOST_PYTHON_STATIC_LIB
+        <python-debugging>on:<define>BOOST_DEBUG_PYTHON
     ;
 }
 else