pgsql: Fix error detection in contrib/pgcrypto's encrypt_iv() and decry

Fix error detection in contrib/pgcrypto's encrypt_iv() and decrypt_iv().

Due to oversights, the encrypt_iv() and decrypt_iv() functions failed to
report certain types of invalid-input errors, and would instead return
random garbage values.

Marko Kreen, per report from Stefan Kaltenbrunner

Branch
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REL9_0_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/a752952d2600c65d06b470f7de43dd068a11f673

Modified Files
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contrib/pgcrypto/pgcrypto.c | 8 ++++----
1 files changed, 4 insertions(+), 4 deletions(-)