gnupg2: port "8192 bit key support" option from gnupg

Closes Homebrew#21291.

Signed-off-by: Adam Vandenberg <[email protected]>

Library/Formula/gnupg2.rb

@@ -5,6 +5,8 @@ class Gnupg2 < Formula
  url 'ftp:https://ftp.gnupg.org/gcrypt/gnupg/gnupg-2.0.20.tar.bz2'
  sha1 '7ddfefa37ee9da89a8aaa8f9059d251b4cd02562'
 
+ option '8192', 'Build with support for private keys of up to 8192 bits'
+
  depends_on 'libgpg-error'
  depends_on 'libgcrypt'
  depends_on 'libksba'
@@ -24,6 +26,8 @@ class Gnupg2 < Formula
  def patches; DATA; end
 
  def install
+ inreplace 'g10/keygen.c', 'max=4096', 'max=8192' if build.include? '8192'
+
  (var/'run').mkpath
 
  ENV['gl_cv_absolute_stdint_h'] = "#{MacOS.sdk_path}/usr/include/stdint.h"