zbackup: revision for protobuf

build with C++11

Closes #29239.

Signed-off-by: ilovezfs <ilovezfs@icloud.com>

Formula/zbackup.rb

@@ -3,7 +3,7 @@ class Zbackup < Formula
   homepage "http://zbackup.org"
   url "https://github.com/zbackup/zbackup/archive/1.4.4.tar.gz"
   sha256 "efccccd2a045da91576c591968374379da1dc4ca2e3dec4d3f8f12628fa29a85"
-  revision 6
+  revision 7
 
   bottle do
     cellar :any
@@ -29,7 +29,11 @@ class Zbackup < Formula
     sha256 "060491c216a145d34a8fd3385b138630718579404e1a2ec2adea284a52699672"
   end
 
+  needs :cxx11
+
   def install
+    ENV.cxx11
+
     # Avoid collision with protobuf 3.x CHECK macro
     inreplace [
       "backup_creator.cc",