pgsql: Consistently use unsigned arithmetic for alignment calculations.

Consistently use unsigned arithmetic for alignment calculations.

This avoids an assumption about the signed number representation.  It is
anticipated to have no functional changes on supported configurations;
many two's complement assumptions remain elsewhere.

Per a suggestion from Andres Freund.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/709170b790c11b4012004a6baf11a0fc6ec950de

Modified Files
--------------
src/backend/access/hash/hashfunc.c |    2 +-
src/include/access/tupmacs.h       |    8 ++++----
src/include/c.h                    |   10 +++++-----
3 files changed, 10 insertions(+), 10 deletions(-)