Replace global "static" -> "STATIC", to allow "analysis builds". Part 1.

Some tools do not support local/static symbols (one example is GNU ld map file).
Exposing all functions will allow to do detailed size comparisons, etc.

Also, added bunch of statics where they were missing, and replaced few identity
functions with global mp_identity().
diff --git a/py/objnone.c b/py/objnone.c
index 7af0b29..3104787 100644
--- a/py/objnone.c
+++ b/py/objnone.c
@@ -12,11 +12,11 @@
     mp_obj_base_t base;
 } mp_obj_none_t;
 
-static void none_print(void (*print)(void *env, const char *fmt, ...), void *env, mp_obj_t self_in, mp_print_kind_t kind) {
+STATIC void none_print(void (*print)(void *env, const char *fmt, ...), void *env, mp_obj_t self_in, mp_print_kind_t kind) {
     print(env, "None");
 }
 
-static mp_obj_t none_unary_op(int op, mp_obj_t o_in) {
+STATIC mp_obj_t none_unary_op(int op, mp_obj_t o_in) {
     switch (op) {
         case RT_UNARY_OP_BOOL: return mp_const_false;
         default: return MP_OBJ_NULL; // op not supported for None
@@ -30,10 +30,10 @@
     .unary_op = none_unary_op,
 };
 
-static const mp_obj_none_t none_obj = {{&none_type}};
+STATIC const mp_obj_none_t none_obj = {{&none_type}};
 const mp_obj_t mp_const_none = (mp_obj_t)&none_obj;
 
 // the stop-iteration object just needs to be something unique
 // it's not the StopIteration exception
-static const mp_obj_none_t stop_it_obj = {{&none_type}};
+STATIC const mp_obj_none_t stop_it_obj = {{&none_type}};
 const mp_obj_t mp_const_stop_iteration = (mp_obj_t)&stop_it_obj;