py: Declare help, input, open builtins in core.
These are *defined* per-port, but why redeclare them again and again.
diff --git a/cc3200/mpconfigport.h b/cc3200/mpconfigport.h
index d4774ad..d3aacc0 100644
--- a/cc3200/mpconfigport.h
+++ b/cc3200/mpconfigport.h
@@ -114,9 +114,6 @@
#define MICROPY_EMERGENCY_EXCEPTION_BUF_SIZE (0)
// extra built in names to add to the global namespace
-extern const struct _mp_obj_fun_builtin_t mp_builtin_help_obj;
-extern const struct _mp_obj_fun_builtin_t mp_builtin_input_obj;
-extern const struct _mp_obj_fun_builtin_t mp_builtin_open_obj;
#define MICROPY_PORT_BUILTINS \
{ MP_OBJ_NEW_QSTR(MP_QSTR_help), (mp_obj_t)&mp_builtin_help_obj }, \
{ MP_OBJ_NEW_QSTR(MP_QSTR_input), (mp_obj_t)&mp_builtin_input_obj }, \
diff --git a/esp8266/mpconfigport.h b/esp8266/mpconfigport.h
index 4aba682..577b373 100644
--- a/esp8266/mpconfigport.h
+++ b/esp8266/mpconfigport.h
@@ -104,7 +104,6 @@
#define MP_PLAT_PRINT_STRN(str, len) mp_hal_stdout_tx_strn_cooked(str, len)
// extra built in names to add to the global namespace
-extern const struct _mp_obj_fun_builtin_t mp_builtin_open_obj;
#define MICROPY_PORT_BUILTINS \
{ MP_OBJ_NEW_QSTR(MP_QSTR_open), (mp_obj_t)&mp_builtin_open_obj },
diff --git a/py/builtin.h b/py/builtin.h
index 35d8910..f63eac7 100644
--- a/py/builtin.h
+++ b/py/builtin.h
@@ -71,6 +71,10 @@
MP_DECLARE_CONST_FUN_OBJ(mp_builtin_round_obj);
MP_DECLARE_CONST_FUN_OBJ(mp_builtin_sorted_obj);
MP_DECLARE_CONST_FUN_OBJ(mp_builtin_sum_obj);
+// Defined by a port, but declared here for simplicity
+MP_DECLARE_CONST_FUN_OBJ(mp_builtin_help_obj);
+MP_DECLARE_CONST_FUN_OBJ(mp_builtin_input_obj);
+MP_DECLARE_CONST_FUN_OBJ(mp_builtin_open_obj);
MP_DECLARE_CONST_FUN_OBJ(mp_namedtuple_obj);
diff --git a/stmhal/mpconfigport.h b/stmhal/mpconfigport.h
index 455239d..6ec92ac 100644
--- a/stmhal/mpconfigport.h
+++ b/stmhal/mpconfigport.h
@@ -97,9 +97,6 @@
#define MICROPY_EMERGENCY_EXCEPTION_BUF_SIZE (0)
// extra built in names to add to the global namespace
-extern const struct _mp_obj_fun_builtin_t mp_builtin_help_obj;
-extern const struct _mp_obj_fun_builtin_t mp_builtin_input_obj;
-extern const struct _mp_obj_fun_builtin_t mp_builtin_open_obj;
#define MICROPY_PORT_BUILTINS \
{ MP_OBJ_NEW_QSTR(MP_QSTR_help), (mp_obj_t)&mp_builtin_help_obj }, \
{ MP_OBJ_NEW_QSTR(MP_QSTR_input), (mp_obj_t)&mp_builtin_input_obj }, \
diff --git a/teensy/mpconfigport.h b/teensy/mpconfigport.h
index 4b2181c..867c4e6 100644
--- a/teensy/mpconfigport.h
+++ b/teensy/mpconfigport.h
@@ -27,9 +27,6 @@
#define MICROPY_EMERGENCY_EXCEPTION_BUF_SIZE (0)
// extra built in names to add to the global namespace
-extern const struct _mp_obj_fun_builtin_t mp_builtin_help_obj;
-extern const struct _mp_obj_fun_builtin_t mp_builtin_input_obj;
-extern const struct _mp_obj_fun_builtin_t mp_builtin_open_obj;
#define MICROPY_PORT_BUILTINS \
{ MP_OBJ_NEW_QSTR(MP_QSTR_help), (mp_obj_t)&mp_builtin_help_obj }, \
{ MP_OBJ_NEW_QSTR(MP_QSTR_input), (mp_obj_t)&mp_builtin_input_obj }, \
diff --git a/unix/mpconfigport.h b/unix/mpconfigport.h
index 28a7e8b..abda432 100644
--- a/unix/mpconfigport.h
+++ b/unix/mpconfigport.h
@@ -259,8 +259,6 @@
#endif
#endif
-extern const struct _mp_obj_fun_builtin_t mp_builtin_input_obj;
-extern const struct _mp_obj_fun_builtin_t mp_builtin_open_obj;
#define MICROPY_PORT_BUILTINS \
{ MP_ROM_QSTR(MP_QSTR_input), MP_ROM_PTR(&mp_builtin_input_obj) }, \
{ MP_ROM_QSTR(MP_QSTR_open), MP_ROM_PTR(&mp_builtin_open_obj) },
diff --git a/windows/mpconfigport.h b/windows/mpconfigport.h
index 203aa04..51d4697 100644
--- a/windows/mpconfigport.h
+++ b/windows/mpconfigport.h
@@ -149,8 +149,6 @@
#define mp_hal_dupterm_tx_strn(s, l)
#endif
-extern const struct _mp_obj_fun_builtin_t mp_builtin_input_obj;
-extern const struct _mp_obj_fun_builtin_t mp_builtin_open_obj;
#define MICROPY_PORT_BUILTINS \
{ MP_OBJ_NEW_QSTR(MP_QSTR_input), (mp_obj_t)&mp_builtin_input_obj }, \
{ MP_OBJ_NEW_QSTR(MP_QSTR_open), (mp_obj_t)&mp_builtin_open_obj },