procmail: clean up and add meta section

pkgs/applications/misc/procmail/default.nix

···
 stdenv.mkDerivation {
   name = "procmail-3.22";
 
-  buildInputs = [ stdenv.cc.libc ];
+  patches = [ ./CVE-2014-3618.patch ];
 
   # getline is defined differently in glibc now. So rename it.
-  installPhase = "
-    mkdir -p \$out/bin
-    sed -e \"s%^RM.*$%RM=`type -f rm | awk '{print $3;}'` -f%\" -i Makefile
-    sed -e \"s%^BASENAME.*%\BASENAME=$out%\" -i Makefile
-    sed -e \"s%^LIBS=.*%LIBS=-lm%\" -i Makefile
-    sed -e \"s%getline%thisgetline%g\" -i src/*.c src/*.h
-    make DESTDIR=\$out install
-   ";
-
-  phases = "unpackPhase patchPhase installPhase";
-
-  patches = [ ./CVE-2014-3618.patch ];
+  postPatch = ''
+    sed -e "s%^RM.*$%#%" -i Makefile
+    sed -e "s%^BASENAME.*%\BASENAME=$out%" -i Makefile
+    sed -e "s%^LIBS=.*%LIBS=-lm%" -i Makefile
+    sed -e "s%getline%thisgetline%g" -i src/*.c src/*.h
+  '';
 
   src = fetchurl {
     url = ftp://ftp.fu-berlin.de/pub/unix/mail/procmail/procmail-3.22.tar.gz;
     sha256 = "05z1c803n5cppkcq99vkyd5myff904lf9sdgynfqngfk9nrpaz08";
   };
 
-  meta.homepage = "http://www.procmail.org/";
+  meta = with stdenv.lib; {
+    description = "Mail processing and filtering utility";
+    homepage = http://www.procmail.org/;
+    license = licenses.gpl2;
+    platforms = platforms.unix;
+    maintainers = with maintainers; [ gebner ];
+  };
 }