[NFC] Add crash test case for _Atomic(_Bool) IRGen.

Author: varungandhi-apple

test/IRGen/Inputs/atomic_bool.h

@@ -0,0 +1 @@
+typedef struct { _Atomic(_Bool) value; } MyAtomicBool;

test/IRGen/Inputs/module.modulemap

@@ -21,3 +21,8 @@ module AutolinkElfCPragmaTransitive {
 module AutolinkModuleMapLink {
   link "autolink-module-map-link"
 }
+
+module AtomicBoolModule {
+  header "atomic_bool.h"
+  export *
+}

test/IRGen/atomic_bool.swift

@@ -0,0 +1,11 @@
+// RUN: not --crash %target-swift-emit-ir %s -I %S/Inputs
+
+import AtomicBoolModule
+
+public func f() -> MyAtomicBool {
+  return MyAtomicBool()
+}
+
+public func g(_ b: MyAtomicBool) {
+  let _ = b
+}