[lldb] Add test for importing ObjC modules in a non-ObjC target

This was previously crashing due to a missing nullptr check (see
e2d8aa6bf7 ). This just adds a test that should
make sure this doesn't crash in case a user ends up in this strange setup.

lldb/test/API/lang/objc/modules-non-objc-target/Makefile

@@ -0,0 +1,3 @@
+C_SOURCES := main.c
+
+include Makefile.rules

lldb/test/API/lang/objc/modules-non-objc-target/TestObjCModulesNonObjCTarget.py

@@ -0,0 +1,26 @@
+"""
+Tests that importing ObjC modules in a non-ObjC target doesn't crash LLDB.
+"""
+
+import lldb
+from lldbsuite.test.decorators import *
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test import lldbutil
+
+class TestCase(TestBase):
+
+    mydir = TestBase.compute_mydir(__file__)
+
+    @skipUnlessDarwin
+    def test(self):
+        self.build()
+        lldbutil.run_to_source_breakpoint(self,"// break here", lldb.SBFileSpec("main.c"))
+
+        # Import foundation to get some ObjC types.
+        self.expect("expr --lang objc -- @import Foundation")
+        # Do something with NSString (which requires special handling when
+        # preparing to run in the target). The expression most likely can't
+        # be prepared to run in the target but it should at least not crash LLDB.
+        self.expect('expr --lang objc -- [NSString stringWithFormat:@"%d", 1];',
+                    error=True,
+                    substrs=["error: The expression could not be prepared to run in the target"])

lldb/test/API/lang/objc/modules-non-objc-target/main.c

@@ -0,0 +1,3 @@
+int main() {
+  return 0; // break here
+}