Don't define sqlite3StrDup in extension-function.c before 3.6.1
Don't define sqlite3StrDup in extension-function.c before 3.6.1

Before that version, sqlite3StrDup was included in SQLite itself.

With this patch builds work back to 3.5.7

xerial/sqlite-jdbc,paramvir-b/sqlite-jdbc,xerial/sqlite-jdbc,xerial/sqlite-jdbc,paramvir-b/sqlite-jdbc,paramvir-b/sqlite-jdbc,paramvir-b/sqlite-jdbc,xerial/sqlite-jdbc