Factor out the code that generates a co-routine for evaluating the SELECT
on the RHS of an INSERT statement so that the same code can potentially
be reused in other places.

FossilOrigin-Name: a93ee09cdc15987848bf9023e69892ce9a5f989e
diff --git a/src/sqliteInt.h b/src/sqliteInt.h
index b42af1f..6f6bfdb 100644
--- a/src/sqliteInt.h
+++ b/src/sqliteInt.h
@@ -2780,6 +2780,7 @@
 # define sqlite3AutoincrementBegin(X)
 # define sqlite3AutoincrementEnd(X)
 #endif
+int sqlite3CodeCoroutine(Parse*, Select*, SelectDest*);
 void sqlite3Insert(Parse*, SrcList*, ExprList*, Select*, IdList*, int);
 void *sqlite3ArrayAllocate(sqlite3*,void*,int,int*,int*);
 IdList *sqlite3IdListAppend(sqlite3*, IdList*, Token*);