Обсуждение: pgsql: Clean up psql variable code a little: eliminate unnecessary tests

Log Message:
-----------
Clean up psql variable code a little: eliminate unnecessary tests in
GetVariable() and be consistent about treatment of the list header.
Motivated by noticing strspn() taking an unreasonable percentage of
runtime --- the call removed from GetVariable() was the only one that
could be in a high-usage path ...

Modified Files:
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    pgsql/src/bin/psql:
        variables.c (r1.24 -> r1.25)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/bin/psql/variables.c.diff?r1=1.24&r2=1.25)