pgsql: Added STRING datatype for Informix compatibility mode.

Log Message:
-----------
Added STRING datatype for Informix compatibility mode. This work is
based on a patch send in by Böszörményi Zoltán <zb@cybertec.at>.

Modified Files:
--------------
    pgsql/src/interfaces/ecpg:
        ChangeLog (r1.396 -> r1.397)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/ecpg/ChangeLog?r1=1.396&r2=1.397)
    pgsql/src/interfaces/ecpg/compatlib:
        Makefile (r1.43 -> r1.44)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/ecpg/compatlib/Makefile?r1=1.43&r2=1.44)
    pgsql/src/interfaces/ecpg/ecpglib:
        data.c (r1.42 -> r1.43)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/ecpg/ecpglib/data.c?r1=1.42&r2=1.43)
        descriptor.c (r1.32 -> r1.33)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/ecpg/ecpglib/descriptor.c?r1=1.32&r2=1.33)
        execute.c (r1.85 -> r1.86)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/ecpg/ecpglib/execute.c?r1=1.85&r2=1.86)
        misc.c (r1.49 -> r1.50)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/ecpg/ecpglib/misc.c?r1=1.49&r2=1.50)
        typename.c (r1.14 -> r1.15)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/ecpg/ecpglib/typename.c?r1=1.14&r2=1.15)
    pgsql/src/interfaces/ecpg/include:
        ecpgtype.h (r1.37 -> r1.38)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/ecpg/include/ecpgtype.h?r1=1.37&r2=1.38)
    pgsql/src/interfaces/ecpg/pgtypeslib:
        Makefile (r1.44 -> r1.45)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/ecpg/pgtypeslib/Makefile?r1=1.44&r2=1.45)
    pgsql/src/interfaces/ecpg/preproc:
        ecpg.header (r1.7 -> r1.8)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/ecpg/preproc/ecpg.header?r1=1.7&r2=1.8)
        ecpg.trailer (r1.9 -> r1.10)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/ecpg/preproc/ecpg.trailer?r1=1.9&r2=1.10)
        type.c (r1.83 -> r1.84)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/ecpg/preproc/type.c?r1=1.83&r2=1.84)
        variable.c (r1.49 -> r1.50)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/ecpg/preproc/variable.c?r1=1.49&r2=1.50)
    pgsql/src/interfaces/ecpg/test/compat_informix:
        test_informix.pgc (r1.4 -> r1.5)

(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/ecpg/test/compat_informix/test_informix.pgc?r1=1.4&r2=1.5)
    pgsql/src/interfaces/ecpg/test/expected:
        compat_informix-test_informix.c (r1.17 -> r1.18)

(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/ecpg/test/expected/compat_informix-test_informix.c?r1=1.17&r2=1.18)
        compat_informix-test_informix.stderr (r1.13 -> r1.14)

(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/ecpg/test/expected/compat_informix-test_informix.stderr?r1=1.13&r2=1.14)
        compat_informix-test_informix.stdout (r1.5 -> r1.6)

(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/ecpg/test/expected/compat_informix-test_informix.stdout?r1=1.5&r2=1.6)