Revert my previous change.

To quote form the standard:
"reaching the } that terminates the main function returns a value of 0."
- 5.1.2.2.3 Program termination in 2ISO/IEC 9899:2012

Pointed out by:	    kib


git-svn-id: svn+ssh://svn.freebsd.org/doc/head@46069 c2e8774f-c49f-e111-b436-862b2bbc8956