bump failing assembly & codegen tests from LLVM 14 to LLVM 15

Author: Lukas Markeffsky

tests/assembly/is_aligned.rs

@@ -1,5 +1,5 @@
 // assembly-output: emit-asm
-// min-llvm-version: 14.0
+// min-llvm-version: 15.0
 // only-x86_64
 // revisions: opt-speed opt-size
 // [opt-speed] compile-flags: -Copt-level=1

tests/codegen/issue-96497-slice-size-nowrap.rs

@@ -3,7 +3,7 @@
 // in some situations, see https://github.com/rust-lang/rust/issues/96497#issuecomment-1112865218
 
 // compile-flags: -O
-// min-llvm-version: 14.0
+// min-llvm-version: 15.0
 
 #![crate_type="lib"]