pgsql: Mark PG_MODULE_MAGIC and PG_FUNCTION_INFO_V1 with PGDLLEXPORT

Log Message:
-----------
Mark PG_MODULE_MAGIC and PG_FUNCTION_INFO_V1 with PGDLLEXPORT
independently from BUILDING_DLL. It is always __declspec(dllexport).

Modified Files:
--------------
pgsql/src/include:
c.h (r1.240 -> r1.241)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/c.h?r1=1.240&r2=1.241)
fmgr.h (r1.65 -> r1.66)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/fmgr.h?r1=1.65&r2=1.66)
pgsql/src/include/port:
cygwin.h (r1.7 -> r1.8)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/port/cygwin.h?r1=1.7&r2=1.8)
win32.h (r1.93 -> r1.94)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/port/win32.h?r1=1.93&r2=1.94)