py: Rename __QSTR_EXTRACT flag to NO_QSTR.
It has more usages than just qstr extraction, for example, embedding (where
people don't care about efficient predefined qstrs).
diff --git a/py/qstr.c b/py/qstr.c
index 24793ff..61202fb 100644
--- a/py/qstr.c
+++ b/py/qstr.c
@@ -93,7 +93,7 @@
10, // set so that the first dynamically allocated pool is twice this size; must be <= the len (just below)
MP_QSTRnumber_of, // corresponds to number of strings in array just below
{
-#ifndef __QSTR_EXTRACT
+#ifndef NO_QSTR
#define QDEF(id, str) str,
#include "genhdr/qstrdefs.generated.h"
#undef QDEF