Added internal Boost Build unit tests making sure its equality tests work as expected. Used tests to explicitly document the standard Boost Jam = && != operator behaviour with ignoring trailing empty strings.

[SVN r46262]

tools/build

@@ -1 +1 @@
-Subproject commit cb6a97af1c1bc38ff66802712355a025fd522655
+Subproject commit 8be0a779221d4b5a6da25bbc19c53e25ae68c9b3