Add [[fallthrough]] attribute to case statements when appropriate.

Author: Cory-Kramer

opensubdiv/bfr/hash.cpp

@@ -388,47 +388,47 @@ void SpookyHash::Short(
     {
     case 15:
     d += ((uint64)u.p8[14]) << 48;
-        // FALLTHRU
+        [[fallthrough]];
     case 14:
         d += ((uint64)u.p8[13]) << 40;
-        // FALLTHRU
+        [[fallthrough]];
     case 13:
         d += ((uint64)u.p8[12]) << 32;
-        // FALLTHRU
+        [[fallthrough]];
     case 12:
         d += u.p32[2];
         c += u.p64[0];
         break;
     case 11:
         d += ((uint64)u.p8[10]) << 16;
-        // FALLTHRU
+        [[fallthrough]];
     case 10:
         d += ((uint64)u.p8[9]) << 8;
-        // FALLTHRU
+        [[fallthrough]];
     case 9:
         d += (uint64)u.p8[8];
-        // FALLTHRU
+        [[fallthrough]];
     case 8:
         c += u.p64[0];
         break;
     case 7:
         c += ((uint64)u.p8[6]) << 48;
-        // FALLTHRU
+        [[fallthrough]];
     case 6:
         c += ((uint64)u.p8[5]) << 40;
-        // FALLTHRU
+        [[fallthrough]];
     case 5:
         c += ((uint64)u.p8[4]) << 32;
-        // FALLTHRU
+        [[fallthrough]];
     case 4:
         c += u.p32[0];
         break;
     case 3:
         c += ((uint64)u.p8[2]) << 16;
-        // FALLTHRU
+        [[fallthrough]];
     case 2:
         c += ((uint64)u.p8[1]) << 8;
-        // FALLTHRU
+        [[fallthrough]];
     case 1:
         c += (uint64)u.p8[0];
         break;