Fix findbugs perf issues

Summary: perf issues flagged by findbugs

Test Plan: Unit Tests

findbugsfilter.xml

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="UTF-8"?>
+
+<FindBugsFilter>
+  <Match classregex=".*ApkDescription$">
+      <BugCode name="OS"/>
+  </Match>
+</FindBugsFilter>

src/com/facebook/buck/apple/clang/HeaderMap.java

@@ -454,7 +454,7 @@ private int addString(String str) {
     }
     putStringByte((byte) 0);
 
-    addedStrings.put(str, new Integer(offset));
+    addedStrings.put(str, offset);
     return offset;
   }
 }

src/com/facebook/buck/cli/TargetsCommand.java

@@ -210,11 +210,10 @@ private void printJsonForTargetsInternal(
     getStdOut().println("[");
 
     ObjectMapper mapper = new ObjectMapper();
-    Iterator<String> keySetIterator = buildIndex.keySet().iterator();
+    Iterator<BuildRule> valueIterator = buildIndex.values().iterator();
 
-    while (keySetIterator.hasNext()) {
-      String key = keySetIterator.next();
-      BuildRule buildRule = buildIndex.get(key);
+    while (valueIterator.hasNext()) {
+      BuildRule buildRule = valueIterator.next();
       BuildTarget buildTarget = buildRule.getBuildTarget();
 
       List<Map<String, Object>> rules;
@@ -273,7 +272,7 @@ private void printJsonForTargetsInternal(
         throw Throwables.propagate(e);
       }
       String output = stringWriter.getBuffer().toString();
-      if (keySetIterator.hasNext()) {
+      if (valueIterator.hasNext()) {
         output += ",";
       }
       getStdOut().println(output);

src/com/facebook/buck/test/XmlTestResultParser.java

@@ -62,7 +62,7 @@ private static TestCaseSummary doParse(String xml) throws IOException {
     for (int i = 0; i < testElements.getLength(); i++) {
       Element node = (Element)testElements.item(i);
       String testName = node.getAttribute("name");
-      long time = Long.valueOf(node.getAttribute("time"));
+      long time = Long.parseLong(node.getAttribute("time"));
       String typeString = node.getAttribute("type");
       ResultType type = ResultType.valueOf(typeString);