.gitignore: ignore all built examples

10-at-a-time

anyauthput

certinfo

chkspeed

cookie_interface

debug

fileupload

fopen

ftp-wildcard

ftpget

ftpgetinfo

ftpgetresp

ftpupload

getinfo

getinmemory

http-post

httpcustomheader

httpput

https

multi-app

multi-debugcallback

multi-double

multi-post

multi-single

persistant

post-callback

postit2

sendrecv

sepheaders

simple

simplepost

simplessl