platform split for pthread and win32 builds so can use pthread-win32 library on Windows with <thrd-api>pthread feature; new C++0x-alike thread class interface on win32.

[SVN r40348]

libs/thread

@@ -1 +1 @@
-Subproject commit 60380afe15148e4a2ec753b1b601ae7cab5a6fcb
+Subproject commit a646153615131fa58b15d1d8bb81d52534f57d86