Start cleaning up 64bit Win warnings

https://codereview.chromium.org/27192003/



git-svn-id: http://skia.googlecode.com/svn/trunk@11764 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/tools/skpdiff/skpdiff_util.cpp b/tools/skpdiff/skpdiff_util.cpp
index 5b19c73..171721c 100644
--- a/tools/skpdiff/skpdiff_util.cpp
+++ b/tools/skpdiff/skpdiff_util.cpp
@@ -130,7 +130,7 @@
     return true;
 #elif SK_BUILD_FOR_WIN32
     char pathDirGlob[MAX_PATH];
-    char pathLength = strlen(path);
+    size_t pathLength = strlen(path);
     strncpy(pathDirGlob, path, pathLength);
 
     if (path[pathLength - 1] == '/' || path[pathLength - 1] == '\\') {