libmtp: fix build in the presence of libgcrypt

Formula/libmtp.rb

@@ -1,30 +1,17 @@
 require 'formula'
 
-class NoGcrypt < Requirement
-  satisfy(:build_env => false) { !Formula["libgcrypt"].installed? }
-
-  def message; <<-EOS.undent
-    This software can fail to compile when libgcrypt is installed.
-    You may need to try:
-      brew unlink libgcrypt
-      brew install libmtp
-      brew link libgcrypt
-    EOS
-  end
-end
-
 class Libmtp < Formula
   homepage 'http://libmtp.sourceforge.net/'
   url 'https://downloads.sourceforge.net/project/libmtp/libmtp/1.1.6/libmtp-1.1.6.tar.gz'
   sha1 'f9e55c75399fc5f4deabcdfa58e1b01b2e6e3283'
 
-  depends_on NoGcrypt
   depends_on "pkg-config" => :build
   depends_on "libusb-compat"
 
   def install
     system "./configure", "--disable-dependency-tracking",
-                          "--prefix=#{prefix}"
+                          "--prefix=#{prefix}",
+                          "--disable-mtpz"
     system "make install"
   end
 end