pgsql: Add lo_truncate() to backend and libpq for large object

Log Message:
-----------
Add lo_truncate() to backend and libpq for large object truncation.

Kris Jurka

Modified Files:
--------------
    pgsql/doc/src/sgml:
        lobj.sgml (r1.44 -> r1.45)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/lobj.sgml.diff?r1=1.44&r2=1.45)
    pgsql/src/backend/libpq:
        be-fsstubs.c (r1.85 -> r1.86)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/libpq/be-fsstubs.c.diff?r1=1.85&r2=1.86)
    pgsql/src/backend/storage/large_object:
        inv_api.c (r1.122 -> r1.123)

(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/storage/large_object/inv_api.c.diff?r1=1.122&r2=1.123)
    pgsql/src/include/catalog:
        pg_proc.h (r1.446 -> r1.447)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/pg_proc.h.diff?r1=1.446&r2=1.447)
    pgsql/src/include/libpq:
        be-fsstubs.h (r1.28 -> r1.29)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/libpq/be-fsstubs.h.diff?r1=1.28&r2=1.29)
    pgsql/src/include/storage:
        large_object.h (r1.36 -> r1.37)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/storage/large_object.h.diff?r1=1.36&r2=1.37)
    pgsql/src/interfaces/libpq:
        exports.txt (r1.14 -> r1.15)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/libpq/exports.txt.diff?r1=1.14&r2=1.15)
        fe-lobj.c (r1.61 -> r1.62)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/libpq/fe-lobj.c.diff?r1=1.61&r2=1.62)
        libpq-fe.h (r1.135 -> r1.136)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/libpq/libpq-fe.h.diff?r1=1.135&r2=1.136)
        libpq-int.h (r1.118 -> r1.119)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/libpq/libpq-int.h.diff?r1=1.118&r2=1.119)
    pgsql/src/test/regress/input:
        largeobject.source (r1.1 -> r1.2)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/input/largeobject.source.diff?r1=1.1&r2=1.2)
    pgsql/src/test/regress/output:
        largeobject.source (r1.1 -> r1.2)

(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/output/largeobject.source.diff?r1=1.1&r2=1.2)