More Windows 64b compilation warning fixes

bench/benchmain.cpp

Index: bench/benchmain.cpp
===================================================================
--- bench/benchmain.cpp	(revision 11997)
+++ bench/benchmain.cpp	(working copy)
@@ -451,13 +451,13 @@
     // Find the longest name of the benches we're going to run to make the output pretty.
     Iter names;
     SkBenchmark* bench;
-    int longestName = 0;
+    size_t longestName = 0;
     while ((bench = names.next()) != NULL) {
         SkAutoTUnref<SkBenchmark> benchUnref(bench);
         if (SkCommandLineFlags::ShouldSkip(FLAGS_match, bench->getName())) {
             continue;
         }
-        const int length = strlen(bench->getName());
+        const size_t length = strlen(bench->getName());
         longestName = length > longestName ? length : longestName;
     }