pgsql: Insert a hack into get_float8_nan (both core and ecpg copies) to

Log Message:
-----------
Insert a hack into get_float8_nan (both core and ecpg copies) to deal with
the fact that NetBSD/mips is currently broken, as per buildfarm member pika.

Also add regression tests to ensure that get_float8_nan and get_float4_nan
are exercised even on platforms where they are not needed by
float8in/float4in.

Zoltn Bszrmnyi and Tom Lane

Modified Files:
--------------
pgsql/src/backend/utils/adt:
float.c (r1.165 -> r1.166)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/float.c?r1=1.165&r2=1.166)
pgsql/src/interfaces/ecpg/ecpglib:
data.c (r1.50 -> r1.51)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/ecpg/ecpglib/data.c?r1=1.50&r2=1.51)
pgsql/src/test/regress/expected:
float4-exp-three-digits.out (r1.9 -> r1.10)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/float4-exp-three-digits.out?r1=1.9&r2=1.10)
float4.out (r1.15 -> r1.16)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/float4.out?r1=1.15&r2=1.16)
float8-exp-three-digits-win32.out (r1.10 -> r1.11)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/float8-exp-three-digits-win32.out?r1=1.10&r2=1.11)
float8-small-is-zero.out (r1.13 -> r1.14)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/float8-small-is-zero.out?r1=1.13&r2=1.14)
float8-small-is-zero_1.out (r1.7 -> r1.8)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/float8-small-is-zero_1.out?r1=1.7&r2=1.8)
float8.out (r1.27 -> r1.28)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/float8.out?r1=1.27&r2=1.28)
pgsql/src/test/regress/sql:
float4.sql (r1.9 -> r1.10)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/sql/float4.sql?r1=1.9&r2=1.10)
float8.sql (r1.16 -> r1.17)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/sql/float8.sql?r1=1.16&r2=1.17)