dirmngr: fix segmentation fault.

Closes Homebrew/legacy-homebrew#32969.
Closes Homebrew/legacy-homebrew#38795.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>

Formula/dirmngr.rb

@@ -18,6 +18,13 @@ class Dirmngr < Formula
   depends_on "libksba"
   depends_on "pth"
 
+  patch :p0 do
+    # patch by upstream developer to fix an API incompatibility with libgcrypt >=1.6.0
+    # causing immediate segfault in dirmngr. see http://bugs.g10code.com/gnupg/issue1590
+    url "http://bugs.g10code.com/gnupg/file419/dirmngr-pth-fix.patch"
+    sha256 "0efbcf1e44177b3546fe318761c3386a11310a01c58a170ef60df366e5160beb"
+  end
+
   def install
     system "./configure", "--disable-dependency-tracking",
                           "--prefix=#{prefix}",
@@ -28,5 +35,6 @@ def install
 
   test do
     system "dirmngr-client", "--help"
+    system "dirmngr", "--help"
   end
 end