Robustify against dots in Jamfile pathnames.

Without this patch, if a Jamfile uses $(__name__).some-rule
for example as generator id, the rule would not be
actually called if Jamfile's path included a dot.


[SVN r59862]

tools/build

@@ -1 +1 @@
-Subproject commit a8f11a4efb541aa86b8938717feb5cfba93f3f2e
+Subproject commit 88c0c9562242d0b0d7c94a3a38bbe04752ea3ad4