pgsql: libpq: Change some static functions to extern

libpq: Change some static functions to extern

This is in preparation of a follow up commit that starts using these
functions from fe-cancel.c.

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/774bcffe4a9853a24e61d758637c0aad2871f1fb

Modified Files
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src/interfaces/libpq/fe-connect.c | 87 ++++++++++++++++++---------------------
src/interfaces/libpq/libpq-int.h  |  5 +++
2 files changed, 46 insertions(+), 46 deletions(-)