Only use readline/history.h if no edit/readline/redline.h
Only use readline/history.h if no edit/readline/redline.h

it seems edit/readline/readline.h and readline/history.h are
incompatible on FreeBSD, so only include one.  Hopefully this works on
OpenBSD still.

feld/Varnish-Cache,zhoualbeart/Varnish-Cache,gauthier-delacroix/Varnish-Cache,gauthier-delacroix/Varnish-Cache,gquintard/Varnish-Cache,chrismoulton/Varnish-Cache,ajasty-cavium/Varnish-Cache,mrhmouse/Varnish-Cache,alarky/varnish-cache-doc-ja,franciscovg/Varnish-Cache,franciscovg/Varnish-Cache,gquintard/Varnish-Cache,varnish/Varnish-Cache,ajasty-cavium/Varnish-Cache,zhoualbeart/Varnish-Cache,franciscovg/Varnish-Cache,alarky/varnish-cache-doc-ja,feld/Varnish-Cache,varnish/Varnish-Cache,chrismoulton/Varnish-Cache,varnish/Varnish-Cache,gquintard/Varnish-Cache,chrismoulton/Varnish-Cache,alarky/varnish-cache-doc-ja,zhoualbeart/Varnish-Cache,franciscovg/Varnish-Cache,gauthier-delacroix/Varnish-Cache,1HLtd/Varnish-Cache,varnish/Varnish-Cache,gauthier-delacroix/Varnish-Cache,franciscovg/Varnish-Cache,1HLtd/Varnish-Cache,zhoualbeart/Varnish-Cache,varnish/Varnish-Cache,feld/Varnish-Cache,mrhmouse/Varnish-Cache,mrhmouse/Varnish-Cache,alarky/varnish-cache-doc-ja,feld/Varnish-Cache,ajasty-cavium/Varnish-Cache,mrhmouse/Varnish-Cache,feld/Varnish-Cache,mrhmouse/Varnish-Cache,alarky/varnish-cache-doc-ja,chrismoulton/Varnish-Cache,chrismoulton/Varnish-Cache,1HLtd/Varnish-Cache,ajasty-cavium/Varnish-Cache,gauthier-delacroix/Varnish-Cache,gquintard/Varnish-Cache,zhoualbeart/Varnish-Cache,1HLtd/Varnish-Cache,ajasty-cavium/Varnish-Cache