Updated libpam-sqlite to support SQLite3

1. Added pam_sqlite3.c
    -> Upgraded to sqlite3.h; All existing SQLite C APIs have been replaced with SQLite3 C APIs.
    -> Updated crypt_make_salt() with sha512; salt length = 16 bits.
    -> Introduced goto statements wherever possible to reduce the risk for not freeing memory, releasing locks & handles, etc during error condition.
    -> Re-aligned code for better readability
    -> Updated SYSLOG for error cases
2. Updated Makefile.in; Introduced a new target for pam_sqlite3.c
3. Updated configure to include sqlite3.h
4. Updated install-module to install pam_sqlite3.so
5. Update .gitingnore to ignore *.swp