pgsql: Adjust signature of walrcv_receive hook.

Adjust signature of walrcv_receive hook.

Commit 314cbfc5da988eff redefined the signature of this hook as
typedef int (*walrcv_receive_type) (char **buffer, int *wait_fd);

But in fact the type of the "wait_fd" variable ought to be pgsocket,
which is what WaitLatchOrSocket expects, and which is necessary if
we want to be able to assign PGINVALID_SOCKET to it on Windows.
So fix that.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/c2dc194bdbf5f84ceb433ed416eb389c1234ebc9

Modified Files
--------------
src/backend/replication/README | 4 ++--
src/backend/replication/libpqwalreceiver/libpqwalreceiver.c | 6 +++---
src/backend/replication/walreceiver.c | 2 +-
src/include/replication/walreceiver.h | 2 +-
4 files changed, 7 insertions(+), 7 deletions(-)