Auto merge of #101312 - nikic:update-llvm-7, r=cuviper

Update LLVM submodule

This updates to the current 15.x branch plus one cherry-pick.

Fixes #100834.
Fixes #101121.

diff --git a/src/llvm-project b/src/llvm-project
index e3be3f64ecac101d14ceda759ba078ad0aaf3747..670e5f673acb736acbfce65e0ffe2c8cd115b93f 160000 (submodule)
--- a/src/llvm-project
+++ b/src/llvm-project
@@ -1 +1 @@
-Subproject commit e3be3f64ecac101d14ceda759ba078ad0aaf3747
+Subproject commit 670e5f673acb736acbfce65e0ffe2c8cd115b93f