superenv: Move Linux-specific bits to extend/os/

Library/Homebrew/extend/ENV/super.rb

@@ -62,8 +62,6 @@ module Superenv
     self["HOMEBREW_ISYSTEM_PATHS"] = determine_isystem_paths
     self["HOMEBREW_INCLUDE_PATHS"] = determine_include_paths
     self["HOMEBREW_LIBRARY_PATHS"] = determine_library_paths
-    self["HOMEBREW_RPATH_PATHS"] = determine_rpath_paths(formula)
-    self["HOMEBREW_DYNAMIC_LINKER"] = determine_dynamic_linker_path
     self["HOMEBREW_DEPENDENCIES"] = determine_dependencies
     self["HOMEBREW_FORMULA_PREFIX"] = formula.prefix unless formula.nil?
 
@@ -185,18 +183,6 @@ module Superenv
     PATH.new(paths).existing
   end
 
-  def determine_extra_rpath_paths(_formula)
-    []
-  end
-
-  def determine_rpath_paths(formula)
-    PATH.new(determine_extra_rpath_paths(formula))
-  end
-
-  def determine_dynamic_linker_path
-    nil
-  end
-
   def determine_dependencies
     deps.map(&:name).join(",")
   end

Library/Homebrew/extend/os/linux/extend/ENV/super.rb

@@ -4,6 +4,13 @@ module Superenv
     (HOMEBREW_SHIMS_PATH/"linux/super").realpath
   end
 
+  # @private
+  def setup_build_environment(formula = nil)
+    generic_setup_build_environment(formula)
+    self["HOMEBREW_DYNAMIC_LINKER"] = determine_dynamic_linker_path
+    self["HOMEBREW_RPATH_PATHS"] = determine_rpath_paths(formula)
+  end
+
   def homebrew_extra_paths
     paths = []
     paths += %w[binutils make].map do |f|
@@ -17,7 +24,7 @@ module Superenv
     paths
   end
 
-  def determine_extra_rpath_paths(formula)
+  def determine_rpath_paths(formula)
     PATH.new(
       formula&.lib,
       "#{HOMEBREW_PREFIX}/lib",