Deprecate rb_eval_cmd, add rb_eval_cmd_kw

rb_eval_cmd takes a safe level, and now that $SAFE is deprecated,
it should be deprecated as well.

Replace with rb_eval_cmd_kw, which takes a keyword flag.  Switch
the two callers to this function.

include/ruby/intern.h

@@ -435,6 +435,7 @@ void rb_attr(VALUE,ID,int,int,int);
 int rb_method_boundp(VALUE, ID, int);
 int rb_method_basic_definition_p(VALUE, ID);
 VALUE rb_eval_cmd(VALUE, VALUE, int);
+VALUE rb_eval_cmd_kw(VALUE, VALUE, int);
 int rb_obj_respond_to(VALUE, ID, int);
 int rb_respond_to(VALUE, ID);
 NORETURN(VALUE rb_f_notimplement(int argc, const VALUE *argv, VALUE obj, VALUE marker));

signal.c

@@ -1043,7 +1043,7 @@ signal_exec(VALUE cmd, int sig)
     EC_PUSH_TAG(ec);
     if ((state = EC_EXEC_TAG()) == TAG_NONE) {
 	VALUE signum = INT2NUM(sig);
-        rb_eval_cmd(cmd, rb_ary_new3(1, signum), 0);
+        rb_eval_cmd_kw(cmd, rb_ary_new3(1, signum), RB_NO_KEYWORDS);
     }
     EC_POP_TAG();
     ec = GET_EC();

variable.c

@@ -526,7 +526,7 @@ rb_define_virtual_variable(
 static void
 rb_trace_eval(VALUE cmd, VALUE val)
 {
-    rb_eval_cmd(cmd, rb_ary_new3(1, val), 0);
+    rb_eval_cmd_kw(cmd, rb_ary_new3(1, val), RB_NO_KEYWORDS);
 }
 
 VALUE

vm_eval.c

@@ -1777,7 +1777,7 @@ rb_eval_string_wrap(const char *str, int *pstate)
 }
 
 VALUE
-rb_eval_cmd(VALUE cmd, VALUE arg, int _level)
+rb_eval_cmd_kw(VALUE cmd, VALUE arg, int kw_splat)
 {
     enum ruby_tag_type state;
     volatile VALUE val = Qnil;		/* OK */
@@ -1786,8 +1786,8 @@ rb_eval_cmd(VALUE cmd, VALUE arg, int _level)
     EC_PUSH_TAG(ec);
     if ((state = EC_EXEC_TAG()) == TAG_NONE) {
 	if (!RB_TYPE_P(cmd, T_STRING)) {
-	    val = rb_funcallv(cmd, idCall, RARRAY_LENINT(arg),
-			      RARRAY_CONST_PTR(arg));
+            val = rb_funcallv_kw(cmd, idCall, RARRAY_LENINT(arg),
+                              RARRAY_CONST_PTR(arg), kw_splat);
 	}
 	else {
 	    val = eval_string_with_cref(rb_vm_top_self(), cmd, NULL, 0, 0);
@@ -1799,6 +1799,13 @@ rb_eval_cmd(VALUE cmd, VALUE arg, int _level)
     return val;
 }
 
+VALUE
+rb_eval_cmd(VALUE cmd, VALUE arg, int _level)
+{
+    rb_warn("rb_eval_cmd will be removed in Ruby 3.0");
+    return rb_eval_cmd_kw(cmd, arg, RB_NO_KEYWORDS);
+}
+
 /* block eval under the class/module context */
 
 static VALUE