Scan the classloader hierarchy for JARs and, optionally, for JARs where
the name doesn't end in .jar and directories that represent exploded
JARs. The JARs under WEB-INF/lib will be skipped as they have been
scanned previously.

This represents a Tomcat-specific extension to the TLD search
order defined in the JSP spec. It allows tag libraries packaged as JAR
files to be shared by web applications by simply dropping them in a
location that all web applications have access to (e.g.,
<CATALINA_HOME>/lib). It also supports some of the weird and
wonderful arrangements present when Tomcat gets embedded.

The set of shared JARs to be scanned for TLDs is narrowed down by
the <tt>noTldJars</tt> class variable, which contains the names of JARs
that are known not to contain any TLDs.

Keep in sync with o.a.j.comiler.TldLocationsCache