pgsql-server: Added free() calls against memory leak in interval.c.

Log Message:
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Added free() calls against memory leak in interval.c.

Tags:
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REL7_4_STABLE

Modified Files:
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pgsql-server/src/interfaces/ecpg/pgtypeslib:
interval.c (r1.7 -> r1.7.2.1)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/interfaces/ecpg/pgtypeslib/interval.c.diff?r1=1.7&r2=1.7.2.1)