[arm] Handle backward jumps properly with TBH (PR#5623).      The Thumb-2 TBH instruction supports only forward jumps, which is what is usually generated for Lswitch. But in some rare cases, the compiler can generate backward jumps for Lswitch. To properly support these cases, we emit appropriate trampolines (following the TBH) for these backward jumps as necessary.
[arm] Handle backward jumps properly with TBH (PR#5623).
    
The Thumb-2 TBH instruction supports only forward jumps, which is what is
usually generated for Lswitch. But in some rare cases, the compiler can
generate backward jumps for Lswitch. To properly support these cases, we
emit appropriate trampolines (following the TBH) for these backward jumps
as necessary.



git-svn-id: e7e61699ce1738538ffebb75374fbea0924bc775@12548 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02

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