This patch will avoid SIGFPE on some geo functions , if PostgreSQL is compiled

This patch will avoid SIGFPE on some geo functions , if PostgreSQL is compiled
with DEC C.

DEC C doesn't handle double values greater than DBL_MAX, but some
PostgreSQL geo functions assign greater than DBL_MAX values to some vars
in some special cases - that couses SIGFPE. I dunno if that is the only place
to fix to work well with DEC C.

Kirill Nosov.