Fix textproc/cgrep after r447548.

Unfortunately a fix did not make it into the previous ghc-update commit.

This backports an upstream fix to the duplicate definition of isSymbolicLink.

Reported by:	antoine
Reviewed by:	pgj
Differential Revision:	https://reviews.freebsd.org/D11960

textproc/cgrep/Makefile

@@ -3,6 +3,7 @@
 
 PORTNAME=	cgrep
 PORTVERSION=	6.4.3
+PORTREVISION=	1
 DISTVERSIONPREFIX=	v
 CATEGORIES=	textproc
 

textproc/cgrep/files/patch-src_Main.hs

@@ -0,0 +1,32 @@
+Backport of:
+From 2f787c5c1ba42ccee2f1ced759b3a4570afa9b28 Mon Sep 17 00:00:00 2001
+From: ilovezfs <ilovezfs@icloud.com>
+Date: Mon, 23 May 2016 03:53:52 -0700
+Subject: [PATCH] cgrep: fix isSymbolicLink collision
+
+System.Directory.isSymbolicLink collides with
+System.PosixCompat.Files.isSymbolicLink (and with
+System.Posix.Files.isSymbolicLink)
+
+This applies the solution proposed here:
+https://github.com/haskell/directory/issues/52#issuecomment-220879392
+--- src/Main.hs.orig	2014-06-21 09:27:05 UTC
++++ src/Main.hs
+@@ -37,7 +37,7 @@ import System.Console.CmdArgs
+ import System.Directory
+ import System.FilePath ((</>), takeFileName)
+ import System.Environment
+-import System.Posix.Files
++import System.Posix.Files as PosixFiles
+ import System.IO
+ import System.Exit
+ 
+@@ -67,7 +67,7 @@ putRecursiveContents opts inchan topdir langs prunedir
+                 status  <- getFileStatus path
+                 lstatus <- getSymbolicLinkStatus path
+                 unless (cpath `Set.member` visited) $
+-                    if isDirectory status && (not (isSymbolicLink lstatus) || deference_recursive opts)
++                    if isDirectory status && (not (PosixFiles.isSymbolicLink lstatus) || deference_recursive opts)
+                        then unless (filename `elem` prunedir)  $
+                            putRecursiveContents opts inchan path langs prunedir (Set.insert cpath visited)
+                        else case getLang opts filename >>= (\f -> f `elemIndex` langs <|> toMaybe 0 (null langs) ) of