checkpkg: Use a pipe to sort package lists

No need to do this after we already wrote the package list to a file.

Signed-off-by: Lukas Fleischer <archlinux@cryptocrack.de>
Signed-off-by: Pierre Schmitz <pierre@archlinux.de>

checkpkg

@@ -69,11 +69,8 @@ for _pkgname in "${pkgname[@]}"; do
 		fi
 	fi
 
-	bsdtar tf "$oldpkg" > "filelist-$_pkgname-old"
-	bsdtar tf "$pkgfile" > "filelist-$_pkgname"
-
-	sort -o "filelist-$_pkgname" "filelist-$_pkgname"
-	sort -o "filelist-$_pkgname-old" "filelist-$_pkgname-old"
+	bsdtar tf "$oldpkg" | sort > "filelist-$_pkgname-old"
+	bsdtar tf "$pkgfile" | sort > "filelist-$_pkgname"
 
 	sdiff -s "filelist-$_pkgname-old" "filelist-$_pkgname"