Add an internal interface that allows the code to take advantage of multiple
cores by pushing subcomputations off into separate threads.  The interface
is not currently used.

FossilOrigin-Name: 0e4d977a4a07d6de50acbf022c7dd947998b8d96
diff --git a/src/sqliteInt.h b/src/sqliteInt.h
index f7f5fd3..f0ccc5c 100644
--- a/src/sqliteInt.h
+++ b/src/sqliteInt.h
@@ -661,6 +661,7 @@
 typedef struct RowSet RowSet;
 typedef struct Savepoint Savepoint;
 typedef struct Select Select;
+typedef struct SQLiteThread SQLiteThread;
 typedef struct SrcList SrcList;
 typedef struct StrAccum StrAccum;
 typedef struct Table Table;
@@ -3307,4 +3308,10 @@
 #define MEMTYPE_PCACHE     0x08  /* Page cache allocations */
 #define MEMTYPE_DB         0x10  /* Uses sqlite3DbMalloc, not sqlite_malloc */
 
+/*
+** Threading interface
+*/
+int sqlite3ThreadCreate(SQLiteThread**,void*(*)(void*),void*);
+int sqlite3ThreadJoin(SQLiteThread*, void**);
+
 #endif /* _SQLITEINT_H_ */