Auto merge of #140914 - Zalathar:asm-bindings, r=compiler-errors

cg_llvm: Clean up some inline assembly bindings

This PR combines a few loosely-related cleanups to LLVM bindings related to inline assembly. These include:
- Replacing `LLVMRustInlineAsm` with LLVM-C's `LLVMGetInlineAsm`
- Adjusting FFI declarations to avoid the need for explicit `as_c_char_ptr` conversions
- Flattening control flow in `inline_asm_call`

There should be no functional changes.

compiler/rustc_codegen_llvm/src/llvm/mod.rs

@@ -441,3 +441,11 @@ pub(crate) fn set_dso_local<'ll>(v: &'ll Value) {
         LLVMRustSetDSOLocal(v, true);
     }
 }
+
+/// Safe wrapper for `LLVMAppendModuleInlineAsm`, which delegates to
+/// `Module::appendModuleInlineAsm`.
+pub(crate) fn append_module_inline_asm<'ll>(llmod: &'ll Module, asm: &[u8]) {
+    unsafe {
+        LLVMAppendModuleInlineAsm(llmod, asm.as_ptr(), asm.len());
+    }
+}