Fix some issues with the fop tool.

* Import boostbook to register `FO`.
* Remove re-initialization check, now overrides previous initialization.
* Set `JAVA_HOME` and `JAVACMD` based on the appropriate parameters.

[SVN r66432]

tools/build

@@ -1 +1 @@
-Subproject commit 5444f1c210e971762602ab8942eafbbb65b6e0ff
+Subproject commit 3c944bab6cb3ebd8ecf90e4199bdaedd8bcd274e