Add fallthroughs to GetMurmurHash3

Source/Core/Common/Hash.cpp

@@ -136,33 +136,46 @@ static u64 GetMurmurHash3(const u8* src, u32 len, u32 samples)
   {
   case 15:
     k2 ^= u64(tail[14]) << 48;
+    [[fallthrough]];
   case 14:
     k2 ^= u64(tail[13]) << 40;
+    [[fallthrough]];
   case 13:
     k2 ^= u64(tail[12]) << 32;
+    [[fallthrough]];
   case 12:
     k2 ^= u64(tail[11]) << 24;
+    [[fallthrough]];
   case 11:
     k2 ^= u64(tail[10]) << 16;
+    [[fallthrough]];
   case 10:
     k2 ^= u64(tail[9]) << 8;
+    [[fallthrough]];
   case 9:
     k2 ^= u64(tail[8]) << 0;
-
+    [[fallthrough]];
   case 8:
     k1 ^= u64(tail[7]) << 56;
+    [[fallthrough]];
   case 7:
     k1 ^= u64(tail[6]) << 48;
+    [[fallthrough]];
   case 6:
     k1 ^= u64(tail[5]) << 40;
+    [[fallthrough]];
   case 5:
     k1 ^= u64(tail[4]) << 32;
+    [[fallthrough]];
   case 4:
     k1 ^= u64(tail[3]) << 24;
+    [[fallthrough]];
   case 3:
     k1 ^= u64(tail[2]) << 16;
+    [[fallthrough]];
   case 2:
     k1 ^= u64(tail[1]) << 8;
+    [[fallthrough]];
   case 1:
     k1 ^= u64(tail[0]) << 0;
     bmix64(h1, h2, k1, k2, c1, c2);