Revert "[llvm][clang] Allocate a new stack instead of spawning a new … (#135865)
…thread to get more stack space (#133173)"
This change breaks the Clang build on Mac AArch64.
This reverts commit d0c973a7a0149db3b71767d4c5a20a31e6a8ed5b. This
reverts commit 429a84f8a4bf559f43f50072747ef49d3e3b2cf1. This reverts
commit 4f64c80d5a23c244f942193e58ecac666c173308.