man: modernize and reduce code duplication

Also use `popen_read` instead of `safe_system` for cleaner argument
passing and write the output with `atomic_write`.

Closes Homebrew/homebrew#46826.

Signed-off-by: Martin Afanasjew <martin@afanasjew.de>

Library/Homebrew/cmd/man.rb

@@ -26,10 +26,19 @@ module Homebrew
       puts "Writing manpages to #{TARGET_PATH}"
 
       Dir["#{SOURCE_PATH}/*.md"].each do |source_file|
-        target_html = DOC_PATH/"#{File.basename(source_file, ".md")}.html"
-        safe_system "ronn --fragment --pipe --organization='Homebrew' --manual='brew' #{source_file} > #{target_html}"
-        target_man = TARGET_PATH/File.basename(source_file, ".md")
-        safe_system "ronn --roff --pipe --organization='Homebrew' --manual='brew' #{source_file} > #{target_man}"
+        args = %W[
+          --pipe
+          --organization=Homebrew
+          --manual=brew
+          #{source_file}
+        ]
+        page = File.basename(source_file, ".md")
+
+        target_html = DOC_PATH/"#{page}.html"
+        target_html.atomic_write Utils.popen_read("ronn", "--fragment", *args)
+
+        target_man = TARGET_PATH/page
+        target_man.atomic_write Utils.popen_read("ronn", "--roff", *args)
       end
     end
   end