pgsql: Move bitmap_hash and bitmap_match to bitmapset.c.

Move bitmap_hash and bitmap_match to bitmapset.c.

The closely-related function bms_hash_value is already defined in that
file, and this change means that hashfn.c no longer needs to depend on
nodes/bitmapset.h. That gets us closer to allowing use of the hash
functions in hashfn.c in frontend code.

Patch by me, reviewed by Suraj Kharage and Mark Dilger.

Discussion: http://postgr.es/m/CA+TgmoaRiG4TXND8QuM6JXFRkM_1wL2ZNhzaUKsuec9-4yrkgw@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/07b95c3d8334f737d4717c91967729f7721e785c

Modified Files
--------------
src/backend/nodes/bitmapset.c   | 23 +++++++++++++++++++++++
src/backend/utils/hash/hashfn.c | 24 ------------------------
src/include/nodes/bitmapset.h   |  2 ++
src/include/utils/hsearch.h     |  2 --
4 files changed, 25 insertions(+), 26 deletions(-)