Revert "[findBugs] Silence DM_STRING_CTOR on PacketLineIn"

This reverts commit 1e510ec20e.

Instead work around the warning by defining our constant by
constructing it through a StringBuilder.

Change-Id: If139509e769d649609c62eff359ebaea5dd286b2
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
CC: Matthias Sohn <matthias.sohn@sap.com>
CC: Chris Aniszczyk <caniszczyk@gmail.com>

org.eclipse.jgit/findBugs/FindBugsExcludeFilter.xml

        <Class name="org.eclipse.jgit.util.TemporaryBuffer$BlockInputStream" />
        <Bug pattern="UR_UNINIT_READ" />
      </Match>
-
-	<!-- Silence invoke inefficient String constructor, we do not want to pool
-		here -->
-     <Match>
-       <Class name="org.eclipse.jgit.transport.PacketLineIn" />
-       <Method name="&lt;clinit&gt;" />
-       <Bug pattern="DM_STRING_CTOR" />
-     </Match>
 </FindBugsFilter>

org.eclipse.jgit/src/org/eclipse/jgit/transport/PacketLineIn.java

 import org.eclipse.jgit.util.RawParseUtils;
 
 class PacketLineIn {
-	static final String END = new String("") /* must not string pool */;
+	/* must not string pool */
+	static final String END = new StringBuilder(0).toString();
 
 	static enum AckNackResult {
 		/** NAK */