Don't touch gvars when compiling for an external back-end.

(cherry picked from commit df2a1c5)

Author: maleadt

src/aotcompile.cpp

@@ -279,7 +279,7 @@ static void jl_ci_cache_lookup(const jl_cgparams_t &cgparams, jl_method_instance
 // takes the running content that has collected in the shadow module and dump it to disk
 // this builds the object file portion of the sysimage files for fast startup, and can
 // also be used be extern consumers like GPUCompiler.jl to obtain a module containing
-// all reachable & inferrrable functions. The `policy` flag switches between the defaul
+// all reachable & inferrrable functions. The `policy` flag switches between the default
 // mode `0` and the extern mode `1`.
 extern "C" JL_DLLEXPORT
 void *jl_create_native(jl_array_t *methods, const jl_cgparams_t cgparams, int _policy)
@@ -404,16 +404,18 @@ void *jl_create_native(jl_array_t *methods, const jl_cgparams_t cgparams, int _p
 
     // move everything inside, now that we've merged everything
     // (before adding the exported headers)
-    for (GlobalObject &G : clone->global_objects()) {
-        if (!G.isDeclaration()) {
-            G.setLinkage(Function::InternalLinkage);
-            makeSafeName(G);
-            addComdat(&G);
+    if (policy != CompilationPolicy::Extern) {
+        for (GlobalObject &G : clone->global_objects()) {
+            if (!G.isDeclaration()) {
+                G.setLinkage(Function::InternalLinkage);
+                makeSafeName(G);
+                addComdat(&G);
 #if defined(_OS_WINDOWS_) && defined(_CPU_X86_64_)
-            // Add unwind exception personalities to functions to handle async exceptions
-            if (Function *F = dyn_cast<Function>(&G))
-                F->setPersonalityFn(juliapersonality_func);
+                // Add unwind exception personalities to functions to handle async exceptions
+                if (Function *F = dyn_cast<Function>(&G))
+                    F->setPersonalityFn(juliapersonality_func);
 #endif
+            }
         }
     }