Use sqlite_errstr instead of sqlite3_errmsg
Use sqlite_errstr instead of sqlite3_errmsg

mpSQLite is free'd with sqlite3_close. It's no more accesible.
Fixes: #48

mc-server/SQLiteCpp,SRombauts/SQLiteCpp,mc-server/SQLiteCpp,sndnvaps/SQLiteCpp,SproutOrc/SQLiteCpp,SRombauts/SQLiteCpp,hongshibao/SQLiteCpp,SproutOrc/SQLiteCpp,SRombauts/SQLiteCpp,sergiosvieira/SQLiteCpp,sndnvaps/SQLiteCpp,mc-server/SQLiteCpp,sergiosvieira/SQLiteCpp,hongshibao/SQLiteCpp,hongshibao/SQLiteCpp,sergiosvieira/SQLiteCpp,SproutOrc/SQLiteCpp,sndnvaps/SQLiteCpp,stelalae/SQLiteCpp