Remove includes from .cabal-file

This is useless at best, and a common source of confusion.

haskell/cabal#10145
sol/hpack#355

Author: sol

network.cabal

@@ -123,7 +123,6 @@ library
 
     default-language: Haskell2010
     include-dirs:     include
-    includes:         HsNet.h HsNetDef.h alignment.h win32defs.h
     install-includes: HsNet.h HsNetDef.h alignment.h win32defs.h
     if os(windows)
         includes:         afunix_compat.h