pgsql: Improve implementation of GEQO's init_tour() function.

Improve implementation of GEQO's init_tour() function.

Rather than filling a temporary array and then copying values to the
output array, we can generate the required random permutation in-place
using the Fisher-Yates shuffle algorithm. This is shorter as well as
more efficient than before. It's pretty unlikely that anyone would
notice a speed improvement, but shorter code is better.

Nathan Wagner, edited a bit by me

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/59464bd6f928ad0da30502cbe9b54baec9ca2c69

Modified Files
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src/backend/optimizer/geqo/geqo_recombination.c | 44 ++++++++++-------------
1 file changed, 19 insertions(+), 25 deletions(-)