Apparently some builds of gcc don't have declaration-after-statement.

This checks for it in configure, and only uses it if it's available.

If it's wrong, somebody please yell at me and tell me why.


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@72539 65c4cc65-6c06-0410-ace0-fbb531ad65f3