Fix init order for R < 4.2

Need to call into R-level `exists()` on these versions

Author: lionel-

src/rlang/rlang.c

@@ -96,28 +96,28 @@ r_obj* r_init_library(r_obj* ns) {
   r_init_library_obj(ns);
   r_init_library_globals(ns);
 
+  shared_x_env = r_parse_eval("new.env(hash = FALSE, parent = baseenv(), size = 1L)", r_envs.base);
+  r_preserve(shared_x_env);
+
+  shared_xy_env = r_parse_eval("new.env(hash = FALSE, parent = baseenv(), size = 1L)", r_envs.base);
+  r_preserve(shared_xy_env);
+
+  shared_xyz_env = r_parse_eval("new.env(hash = FALSE, parent = baseenv(), size = 1L)", r_envs.base);
+  r_preserve(shared_xyz_env);
+
+  r_init_library_sym();
+  r_init_library_eval();
+  r_init_library_env();
   r_init_rlang_ns_env();
   r_init_library_arg();
   r_init_library_call();
   r_init_library_cnd();
   r_init_library_dyn_array();
-  r_init_library_env();
-  r_init_library_eval();
   r_init_library_fn();
   r_init_library_quo();
   r_init_library_session();
-  r_init_library_sym();
   r_init_library_stack();
 
-  shared_x_env = r_parse_eval("new.env(hash = FALSE, parent = baseenv(), size = 1L)", r_envs.base);
-  r_preserve(shared_x_env);
-
-  shared_xy_env = r_parse_eval("new.env(hash = FALSE, parent = baseenv(), size = 1L)", r_envs.base);
-  r_preserve(shared_xy_env);
-
-  shared_xyz_env = r_parse_eval("new.env(hash = FALSE, parent = baseenv(), size = 1L)", r_envs.base);
-  r_preserve(shared_xyz_env);
-
   // Return a SEXP so the init function can be called from R
   return r_null;
 }