Adjust blank lines around PG_MODULE_MAGIC defines, for consistency

contrib/dict_int/dict_int.c

contrib/earthdistance/earthdistance.c

contrib/intarray/_int_op.c

contrib/lo/lo.c

contrib/passwordcheck/passwordcheck.c

contrib/pg_buffercache/pg_buffercache_pages.c

contrib/pg_freespacemap/pg_freespacemap.c

contrib/pg_stat_statements/pg_stat_statements.c

contrib/pg_trgm/trgm_op.c

contrib/pgrowlocks/pgrowlocks.c

contrib/pgstattuple/pgstattuple.c

contrib/postgres_fdw/postgres_fdw.c

contrib/sslinfo/sslinfo.c

contrib/tcn/tcn.c

contrib/test_decoding/test_decoding.c

contrib/test_parser/test_parser.c

contrib/test_shm_mq/test.c

contrib/uuid-ossp/uuid-ossp.c

contrib/xml2/xpath.c

src/backend/snowball/dict_snowball.c