[ARM] Mark labels in skipAlignedDPRCS2Spills as fallthrough (NFC).
[ARM] Mark labels in skipAlignedDPRCS2Spills as fallthrough (NFC).

The comment at the top of the switch statement indicates that the
fall-through behavior is intentional. By using LLVM_FALLTHROUGH,
-Wimplicit-fallthrough are silenced, which is enabled by default in GCC
7.



git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@309272 91177308-0d34-0410-b5e6-96231b3b80d8

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