#29 Fix autoconf check to be C99 compliant.

[Pete Fordham]

Exit is defined in stdlib.h which isn't included. Changed code to use return from main directly instead.

See attached patch. Fixed as part of https://fedoraproject.org/wiki/Toolchain/PortingToModernC.

[Ozkan Sezer]

The patch is applied to git repo as commit b40620a5fba15c72bea24fca6679be7c9206f747

Thanks. Closing the ticket.