pgsql: Increase size of bgw_library_name.

Increase size of bgw_library_name.

This commit increases the size of the bgw_library_name member of
the BackgroundWorker struct from BGW_MAXLEN (96) bytes to MAXPGPATH
(default of 1024) bytes so that it can store longer file names
(e.g., absolute paths).

Author: Yurii Rashkovskii
Reviewed-by: Daniel Gustafsson, Aleksander Alekseev
Discussion: https://postgr.es/m/CA%2BRLCQyjFV5Y8tG5QgUb6gjteL4S3p%2B1gcyqWTqigyM93WZ9Pg%40mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/957845789bb97dde2cb1ee11c1a769984131adf6

Modified Files
--------------
doc/src/sgml/bgworker.sgml                 | 2 +-
src/backend/postmaster/bgworker.c          | 2 +-
src/backend/replication/logical/launcher.c | 4 ++--
src/include/postmaster/bgworker.h          | 2 +-
4 files changed, 5 insertions(+), 5 deletions(-)