pgsql: Refactor some network.c code to create cidr_set_masklen_internal

Refactor some network.c code to create cidr_set_masklen_internal().

Merge several copies of "copy an inet value and adjust the mask length"
code to create a single, conveniently C-callable function. This function
is exported for future use by inet SPGiST support, but it's good cleanup
anyway since we had three slightly-different-for-no-good-reason copies.

(Extracted from a larger patch, to separate new code from refactoring
of old code)

Emre Hasegeli

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/7b405b3e04779fc0a026c9c6ac3e06194948b253

Modified Files
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src/backend/utils/adt/network.c | 109 +++++++++++-----------------------------
src/include/utils/inet.h | 5 +-
2 files changed, 33 insertions(+), 81 deletions(-)