pgsql: Add underscores to SSL CERT macro names, for clarity and

Log Message:
-----------
Add underscores to SSL CERT macro names, for clarity and consistency
with be-secure.c.

Modified Files:
--------------
pgsql/src/interfaces/libpq:
fe-secure.c (r1.77 -> r1.78)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/libpq/fe-secure.c.diff?r1=1.77&r2=1.78)