tsan: don't leave unmapped hole in non-app memory

If an app mmaps lots of memory, a user mmap may end up
in the tsan region for traces. Shadow for this range
overlaps with shadow for other user regions.
This causes havok: from false positives to crashes.
Don't leave unmapped holes in the traces region.

Reviewed-in: https://reviews.llvm.org/D96697
GitOrigin-RevId: 0984b8de0b0d5d178a8e6e5de1eb89f29493a89e
3 files changed