Add newline at end of tools/skdiff_html.h to happify the housekeeping bot

TBR=bungeman
Review URL: https://codereview.appspot.com/6893043

git-svn-id: http://skia.googlecode.com/svn/trunk@6684 2bbb7eff-a529-9590-31e7-b0007b416f81

tools/skdiff_html.h

@@ -18,4 +18,4 @@ void print_diff_page(const int matchCount,
                      const SkString& comparisonDir,
                      const SkString& outputDir);
 
-#endif
+#endif