Update bbv2 instructions.

Update Jamfile with better ICU support.


[SVN r36691]

libs/regex

@@ -1 +1 @@
-Subproject commit c1722ff3de07d79f96edf1fbe454657addb579c6
+Subproject commit fdf8aa83eca1d6643dd82d1974019a4bf42a1d18