Make AGRP inlineable into jitted code

It'll break once we add frame introspection info to it, but
for now it just needed some massaging.

src/codegen/runtime_hooks.cpp

@@ -170,7 +170,7 @@ void initGlobalFuncs(GlobalState& g) {
     g.funcs.malloc = addFunc((void*)malloc, g.i8_ptr, g.i64);
     g.funcs.free = addFunc((void*)free, g.void_, g.i8_ptr);
 
-    g.funcs.allowGLReadPreemption = addFunc((void*)threading::allowGLReadPreemption, g.void_);
+    g.funcs.allowGLReadPreemption = getFunc((void*)threading::allowGLReadPreemption, "allowGLReadPreemption");
 
     GET(softspace);
 

src/core/threading.h

@@ -89,7 +89,8 @@ void _allowGLReadPreemption();
 // only be accessed by the thread that holds the gil:
 extern int gil_check_count;
 extern std::atomic<int> threads_waiting_on_gil;
-inline void allowGLReadPreemption() {
+extern "C" inline void allowGLReadPreemption() __attribute__((visibility("default")));
+extern "C" inline void allowGLReadPreemption() {
 #if ENABLE_SAMPLING_PROFILER
     if (unlikely(sigprof_pending)) {
         // Output multiple stacktraces if we received multiple signals
@@ -167,7 +168,8 @@ inline void promoteGL() {
 }
 inline void demoteGL() {
 }
-inline void allowGLReadPreemption() {
+extern "C" inline void allowGLReadPreemption() __attribute__((visibility("default")));
+extern "C" inline void allowGLReadPreemption() {
 }
 #endif