remove unnecessary check before unregister/1

Reduce cpu cycles for `unregister/1` by removing the check to see
if it is already registered. Now it simply returns `true` if the
process is successful or raises a `badarg` error on failure,
following the expected outputs for OTP.

Signed-off-by: Winford <dwinford@pm.me>

src/libAtomVM/globalcontext.c

@@ -135,10 +135,10 @@ void globalcontext_register_process(GlobalContext *glb, int atom_index, int loca
     linkedlist_append(&glb->registered_processes, &registered_process->registered_processes_list_head);
 }
 
-void globalcontext_unregister_process(GlobalContext *glb, int atom_index)
+bool globalcontext_unregister_process(GlobalContext *glb, int atom_index)
 {
     if (!glb->registered_processes) {
-        return;
+        return false;
     }
 
     struct RegisteredProcess *registered_processes = GET_LIST_ENTRY(glb->registered_processes, struct RegisteredProcess, registered_processes_list_head);
@@ -149,10 +149,12 @@ void globalcontext_unregister_process(GlobalContext *glb, int atom_index)
         if (p->atom_index == atom_index) {
             linkedlist_remove(&glb->registered_processes, &p->registered_processes_list_head);
             free(p);
-            break;
+            return true;
         }
         p = GET_LIST_ENTRY(p->registered_processes_list_head.next, struct RegisteredProcess, registered_processes_list_head);
     } while (p != registered_processes);
+
+    return false;
 }
 
 int globalcontext_get_registered_process(GlobalContext *glb, int atom_index)

src/libAtomVM/nifs.c

@@ -793,14 +793,12 @@ static term nif_erlang_unregister_1(Context *ctx, int argc, term argv[])
 
     int atom_index = term_to_atom_index(reg_name_term);
 
-    // must be a registered name.
-    if (UNLIKELY(globalcontext_get_registered_process(ctx->global, atom_index) == 0)) {
-        RAISE_ERROR(BADARG_ATOM);
+    bool res = globalcontext_unregister_process(ctx->global, atom_index);
+    if (res) {
+        return TRUE_ATOM;
     }
 
-    globalcontext_unregister_process(ctx->global, atom_index);
-
-    return TRUE_ATOM;
+    RAISE_ERROR(BADARG_ATOM);
 }
 
 static term nif_erlang_whereis_1(Context *ctx, int argc, term argv[])