add a debug subcommand for printing LLVM integer type alignment
Useful when debugging why upgrading from LLVM 17 to 18 caused C ABI
regressions. Turns out LLVM 18 does the following insane thing:
```diff
-[nix-shell:~/dev/zig/build-llvm17]$ stage4/bin/zig llvm-ints i386-linux-musl
+[nix-shell:~/src/zig/build-llvm18]$ stage4/bin/zig llvm-ints i386-linux-musl
LLVMABIAlignmentOfType(i1) == 1
LLVMABIAlignmentOfType(i8) == 1
LLVMABIAlignmentOfType(i16) == 2
LLVMABIAlignmentOfType(i32) == 4
LLVMABIAlignmentOfType(i64) == 4
-LLVMABIAlignmentOfType(i128) == 4
-LLVMABIAlignmentOfType(i256) == 4
+LLVMABIAlignmentOfType(i128) == 16
+LLVMABIAlignmentOfType(i256) == 16
```
708894cf99Andrew Kelley committed on 5/9/2024, 2:37:29 AMparent6730b36