pgsql: libpq: Add pqReleaseConnHosts function

libpq: Add pqReleaseConnHosts function

In a follow up commit we'll need to free this connhost field in a
function defined in fe-cancel.c, so here we extract the logic to a
dedicated extern function.

Author: Jelte Fennema-Nio <jelte.fennema@microsoft.com>
Discussion: https://postgr.es/m/AM5PR83MB0178D3B31CA1B6EC4A8ECC42F7529@AM5PR83MB0178.EURPRD83.prod.outlook.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/53747f722228d2cd4d7054c4d509b27dc89306ae

Modified Files
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src/interfaces/libpq/fe-connect.c | 39 ++++++++++++++++++++++++++-------------
src/interfaces/libpq/libpq-int.h  |  1 +
2 files changed, 27 insertions(+), 13 deletions(-)