Improve SQLite3 configuration test

Reference an SQLite3 function to verify that the library is being
linked.  Discovered that the test didn't do this when I switched the
Windows configure to use a compile test to determine whether the
system has SQLite3.  The test passed even though the initial
configure changes failed to provide the test with information about
the SQLite3 libraries.

Change-Id: I3114cfc2dec3a42a60c8e1e432eb8375b440d7e0
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>

config.tests/unix/sqlite/sqlite.cpp

@@ -35,5 +35,6 @@
 
 int main(int, char **)
 {
+    sqlite3_open_v2(0, 0, 0, 0);
     return 0;
 }