Clarify a variable name in SplitZipStep.

Summary:
I'm going to be adding some complexity to this variable, so give it a
more specific name.

Test Plan: Unit.
diff --git a/src/com/facebook/buck/android/SplitZipStep.java b/src/com/facebook/buck/android/SplitZipStep.java
index ab468d4..d3b85d1 100644
--- a/src/com/facebook/buck/android/SplitZipStep.java
+++ b/src/com/facebook/buck/android/SplitZipStep.java
@@ -172,21 +172,21 @@
 
     return new Predicate<String>() {
       @Override
-      public boolean apply(String name) {
+      public boolean apply(String classFileName) {
         // This is a bit of a hack.  DX automatically strips non-class assets from the primary
         // dex (because the output is classes.dex, which cannot contain assets), but not from
         // secondary dex jars (because the output is a jar that can contain assets), so we put
         // all assets in the primary jar to ensure that they get dropped.
-        if (!name.endsWith(".class")) {
+        if (!classFileName.endsWith(".class")) {
           return true;
         }
 
-        if (primaryDexClassNames.contains(name)) {
+        if (primaryDexClassNames.contains(classFileName)) {
           return true;
         }
 
         for (String substr : SplitZipStep.this.primaryDexSubstrings) {
-          if (name.contains(substr)) {
+          if (classFileName.contains(substr)) {
             return true;
           }
         }