[clang] [llvm] [NFC] Replace more DenseMaps with SmallDenseMaps (PR #111836)

[Jeremy Morse via cfe-commits]

jmorse wrote:

Undid the format-changes in this PR. For context: I've been building profiles of all DenseMap allocations across a build of the CTMark suite to find DenseMaps that a) are frequently used and b) usually have a small number of elements, making them good candidates for initial stack allocations. This patch one of the results of that profile-building, the touched DenseMaps are all reasonably frequently used, and using SmallDenseMap yields a small compile-time improvement.

https://github.com/llvm/llvm-project/pull/111836