interpolate sqlite3 lib in krb5-config

Commit 7e6b558d2a261228806c0998f3be83985bb1bf3e updated krb5-config to include sqlite. However, the value was not actually being interpolated if a user ran eg `./configure --with-sqlite3=/foo`.

This pull request adds `@LIB_sqlite3@` to the list of values that get interpolated during the krb5-config build.