pgsql: Clarify the new Red-Black post-order traversal code a bit.

Clarify the new Red-Black post-order traversal code a bit.

Coverity complained about the for(;;) loop, because it never actually
iterated. It was used just to be able to use "break" to exit it early. I
agree with Coverity, that's a bit confusing, so refactor the code to
use if-else instead.

While we're at it, use a local variable to hold the "current" node. That's
shorter and clearer than referring to "iter->last_visited" all the time.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/e21db14b8a6696a2b704b89df9c4be9cd0ea8a33

Modified Files
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src/backend/lib/rbtree.c | 46 ++++++++++++++++++++++++----------------------
1 file changed, 24 insertions(+), 22 deletions(-)