Avoid crash on some 64b ARM NEON platforms.

src/opts/SkXfermode_opts_arm_neon.cpp

 #include "SkXfermode.h"
 #include "SkXfermode_proccoeff.h"
 #include "SkColorPriv.h"
 
 #include <arm_neon.h>
 #include "SkColor_opts_neon.h"
 #include "SkXfermode_opts_arm_neon.h"
 
 #define SkAlphaMulAlpha(a, b)   SkMulDiv255Round(a, b)
 
@@ skipping 800 matching lines @@
                 "blr    %[proc]                        \t\n"
                 "st4    {v0.8b - v3.8b}, [%[dst]], #32 \t\n"
                 : [src] "+&r" (src), [dst] "+&r" (dst)
                 : [proc] "r" (procSIMD)
                 : "cc", "memory",
                   /* We don't know what proc is going to clobber so we must
                    * add everything that is not callee-saved.
                    */
                   "x0", "x1", "x2", "x3", "x4", "x5", "x6", "x7", "x8", "x9",
                   "x10", "x11", "x12", "x13", "x14", "x15", "x16", "x17", "x18",
+                  "x30", /* x30 implicitly clobbered by blr */
                   "v0", "v1", "v2", "v3", "v4", "v5", "v6", "v7", "v16", "v17",
                   "v18", "v19", "v20", "v21", "v22", "v23", "v24", "v25", "v26",
                   "v27", "v28", "v29", "v30", "v31"
             );
 
 #endif // #ifdef SK_CPU_ARM32
 
             count -= 8;
         }
         // Leftovers
@@ skipping 183 matching lines @@
 
     if (procSIMD != NULL) {
         return SkNEW_ARGS(SkNEONProcCoeffXfermode, (rec, mode, procSIMD));
     }
     return NULL;
 }
 
 SkXfermodeProc SkPlatformXfermodeProcFactory_impl_neon(SkXfermode::Mode mode) {
     return gNEONXfermodeProcs1[mode];
 }