enable patchelf.rb writing for devs.

Library/Homebrew/os/linux/global.rb

 # frozen_string_literal: true
 
 # enables experimental patchelf.rb write support.
-HOMEBREW_PATCHELF_RB_WRITE = ENV["HOMEBREW_PATCHELF_RB_WRITE"].present?.freeze
+HOMEBREW_PATCHELF_RB_WRITE = (
+  ENV["HOMEBREW_NO_PATCHELF_RB_WRITE"].blank? &&
+  (ENV["HOMEBREW_PATCHELF_RB_WRITE"].present? ||
+   (ENV["CI"].blank? && ENV["HOMEBREW_DEVELOPER"].present?))
+).freeze
 
 module Homebrew
   DEFAULT_PREFIX ||= if Homebrew::EnvConfig.force_homebrew_on_linux?