use cabal-tweak-drop-dep for mtl-compat

hledger-mtl-compat.patch

@@ -1,26 +0,0 @@
---- hledger-0.27.1/hledger.cabal~	2016-05-28 02:34:17.000000000 +0900
-+++ hledger-0.27.1/hledger.cabal	2016-09-05 16:35:19.499499817 +0900
-@@ -69,7 +69,6 @@
-     , haskeline >= 0.6 && <= 0.8
-     , HUnit
-     , mtl
--    , mtl-compat
-     , old-time
-     , parsec >= 3
-     , process
-@@ -143,7 +142,6 @@
-     , haskeline >= 0.6 && <= 0.8
-     , HUnit
-     , mtl
--    , mtl-compat
-     , old-time
-     , parsec >= 3
-     , process
-@@ -196,7 +194,6 @@
-     , haskeline >= 0.6 && <= 0.8
-     , HUnit
-     , mtl
--    , mtl-compat
-     , old-time
-     , parsec >= 3
-     , process

hledger.spec

@@ -13,7 +13,6 @@ Summary:        The main command-line interface for the hledger accounting tool
 License:        GPLv3
 Url:            https://hackage.haskell.org/package/%{name}
 Source0:        https://hackage.haskell.org/package/%{name}-%{version}/%{name}-%{version}.tar.gz
-Patch0:         hledger-mtl-compat.patch
 
 BuildRequires:  ghc-Cabal-devel
 BuildRequires:  ghc-rpm-macros
@@ -82,7 +81,7 @@ This package provides the Haskell %{name} library development files.
 
 %prep
 %setup -q
-%patch0 -p1 -b .orig
+cabal-tweak-drop-dep mtl-compat
 
 
 %build