Remove `mrb_run` from `MRB_API`; #4488

`mrb_run` requires to push callinfo stack before calling, which is very
hard from outside of `vm.c`. So there should be virtually no correct
usage of the function, hence the cause of #4488. We removed it.

You can use `mrb_top_run(mrb, proc, self, 0)` instead of
`mrb_run(mrb, proc self)`.

include/mruby.h

@@ -1150,7 +1150,6 @@ MRB_API void mrb_close(mrb_state *mrb);
 MRB_API void* mrb_default_allocf(mrb_state*, void*, size_t, void*);
 
 MRB_API mrb_value mrb_top_self(mrb_state *mrb);
-MRB_API mrb_value mrb_run(mrb_state *mrb, struct RProc* proc, mrb_value self);
 MRB_API mrb_value mrb_top_run(mrb_state *mrb, struct RProc *proc, mrb_value self, unsigned int stack_keep);
 MRB_API mrb_value mrb_vm_run(mrb_state *mrb, struct RProc *proc, mrb_value self, unsigned int stack_keep);
 MRB_API mrb_value mrb_vm_exec(mrb_state *mrb, struct RProc *proc, const mrb_code *iseq);

src/vm.c

@@ -324,6 +324,7 @@ cipop(mrb_state *mrb)
 }
 
 void mrb_exc_set(mrb_state *mrb, mrb_value exc);
+static mrb_value mrb_run(mrb_state *mrb, struct RProc* proc, mrb_value self);
 
 static void
 ecall(mrb_state *mrb)
@@ -2808,7 +2809,7 @@ RETRY_TRY_BLOCK:
   MRB_END_EXC(&c_jmp);
 }
 
-MRB_API mrb_value
+static mrb_value
 mrb_run(mrb_state *mrb, struct RProc *proc, mrb_value self)
 {
   if (mrb->c->ci->argc < 0) {