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