Update more directories under src/ to follow C++11 style rule for {virtual,override}.

src/opts/SkXfermode_opts_arm_neon.h

Index: src/opts/SkXfermode_opts_arm_neon.h
diff --git a/src/opts/SkXfermode_opts_arm_neon.h b/src/opts/SkXfermode_opts_arm_neon.h
index cc8c76d1eda7296843fd2f47b3d7c14504a6d418..e3c97786a2c9c525f2e070d324d616e2f8124e53 100644
--- a/src/opts/SkXfermode_opts_arm_neon.h
+++ b/src/opts/SkXfermode_opts_arm_neon.h
@@ -9,10 +9,10 @@ public:
                             void* procSIMD)
             : INHERITED(rec, mode), fProcSIMD(procSIMD) {}
 
-    virtual void xfer32(SkPMColor dst[], const SkPMColor src[], int count,
-                        const SkAlpha aa[]) const override;
-    virtual void xfer16(uint16_t* SK_RESTRICT dst, const SkPMColor* SK_RESTRICT src,
-                        int count, const SkAlpha* SK_RESTRICT aa) const override;
+    void xfer32(SkPMColor dst[], const SkPMColor src[], int count,
+                const SkAlpha aa[]) const override;
+    void xfer16(uint16_t* SK_RESTRICT dst, const SkPMColor* SK_RESTRICT src,
+                int count, const SkAlpha* SK_RESTRICT aa) const override;
 
     SK_TO_STRING_OVERRIDE()