Change StringBuffer in favor of StringBuilder.

Delete unused import.

No boxing

Discussed in dev list https://mail-archives.apache.org/mod_mbox/ant-dev/202106.mbox/%3c2e2ef67a-7d96-adfc-f050-efaccab7e6c2@apache.org%3e

https://bz.apache.org/bugzilla/show_bug.cgi?id=65539

findResources(String, boolean) can unnecessarily search the parent

Implement `ClassLoader#findResource(String)`

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Merge tag 'rel/1.10.11' and prepare for next iteration

Apache Ant 1.10.11

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Merge tag 'rel/1.9.16' and prepare for next iteration

Apache Ant 1.9.16

While target execution tasks are "perform()"ed and datatypes are "maybeConfigure()"d.

Starting Java 17, System.setSecurityManager() usage is deprecated (for removal) as noted in https://openjdk.java.net/jeps/411.
The code here was just calling getSecurityManager() and then in a finally block setting it back using setSecurityManager(). However, we aren't setting any other security manager in between these calls.
Looking at the code history, it appears that at one point back in 2001, we were indeed setting a custom security manager (commit 41893fdb30) but that was then reverted in commit ff4e823ee2. So this current piece of code is practically doing nothing.

see https://bz.apache.org/bugzilla/show_bug.cgi?id=65316

This closes #147 pull request at github/apache/ant repo.