p7zip: enhanced encryption strength

There was a bug in 7zip AES encryption. To fix this the size of random initialization vector was
increased from 64-bit to 128-bit and the pseudo-random number generator was improved.
It has been reported here: https://sourceforge.net/p/sevenzip/bugs/2176/

Keka fixes this in https://github.com/aonez/Keka/issues/379 and provided a patch against p7zip.

Closes #42565.

Signed-off-by: Sean Molenaar <smillerdev@me.com>

Formula/p7zip.rb

@@ -3,7 +3,7 @@ class P7zip < Formula
   homepage "https://p7zip.sourceforge.io/"
   url "https://downloads.sourceforge.net/project/p7zip/p7zip/16.02/p7zip_16.02_src_all.tar.bz2"
   sha256 "5eb20ac0e2944f6cb9c2d51dd6c4518941c185347d4089ea89087ffdd6e2341f"
-  revision 1
+  revision 2
 
   bottle do
     cellar :any_skip_relocation
@@ -20,6 +20,11 @@ class P7zip < Formula
           "patches/13-CVE-2017-17969.patch"
   end
 
+  patch :p4 do
+    url "https://github.com/aonez/Keka/files/2940620/15-Enhanced-encryption-strength.patch.zip"
+    sha256 "838dd2175c3112dc34193e99b8414d1dc1b2b20b861bdde0df2b32dbf59d1ce4"
+  end
+
   def install
     mv "makefile.macosx_llvm_64bits", "makefile.machine"
     system "make", "all3",