build: actually make sqlite mandatory

Change-Id: I9f7183c6a1e1b3a4bc887a67faf2a1c4dfb44762
diff --git a/configure.ac b/configure.ac
index 189a53a..ce0010c 100644
--- a/configure.ac
+++ b/configure.ac
@@ -33,10 +33,7 @@
 PKG_CHECK_MODULES(LIBOSMOVTY, libosmovty >= 0.9.0)
 PKG_CHECK_MODULES(LIBOSMOABIS, libosmoabis >= 0.3.2)
 
-found_sqlite3=yes
-PKG_CHECK_MODULES(SQLITE3, sqlite3, ,found_sqlite3=no)
-AM_CONDITIONAL(HAVE_SQLITE3, test "$found_sqlite3" = yes)
-AC_SUBST(found_sqlite3)
+PKG_CHECK_MODULES(SQLITE3, sqlite3)
 
 AC_CONFIG_MACRO_DIR([m4])