When building the alloca for a local variable, set its name separately from building the instruction so that it's preserved even in -Asserts builds.
When building the alloca for a local variable, set its name
separately from building the instruction so that it's
preserved even in -Asserts builds.

Employ C++'s mystical "comment" feature to discourage
breaking this in the future.

git-svn-id: ffe668792ed300d6c2daa1f6eba2e0aa28d7ec6c@246991 91177308-0d34-0410-b5e6-96231b3b80d8

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