[msan] Update origin for the entire destination range on memory store.
[msan] Update origin for the entire destination range on memory store.

Previously we always stored 4 bytes of origin at the destination address
even for 8-byte (and longer) stores.

This should fix rare missing, or incorrect, origin stacks in MSan reports.


git-svn-id: c199f293c43da69278bea8e88f92242bf3aa95f7@226658 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/compiler-rt,llvm-mirror/compiler-rt,llvm-mirror/compiler-rt,llvm-mirror/compiler-rt,llvm-mirror/compiler-rt