Handle SrcMgr diagnostics

This is how InlineAsm diagnostics with source information are
reported now. Previously a separate InlineAsm diagnostic handler
was used.

src/test/ui/llvm-asm/issue-69092.rs

@@ -1,5 +1,7 @@
 // build-fail
 // ignore-emscripten no asm! support
+// The error message differs slightly between LLVM versions
+// min-llvm-version: 13.0
 // Regression test for #69092
 
 #![feature(llvm_asm)]
@@ -7,5 +9,5 @@
 
 fn main() {
     unsafe { llvm_asm!(".ascii \"Xen\0\""); }
-    //~^ ERROR: expected string in '.ascii' directive
+    //~^ ERROR: expected string
 }

src/test/ui/llvm-asm/issue-69092.stderr

@@ -1,5 +1,5 @@
-error: expected string in '.ascii' directive
-  --> $DIR/issue-69092.rs:9:14
+error: expected string
+  --> $DIR/issue-69092.rs:11:14
    |
 LL |     unsafe { llvm_asm!(".ascii \"Xen\0\""); }
    |              ^