fix(native_comp): improve env setup patch fixing potential issues

The old patch would dynamically glob within
Emacs.app/Contents/MacOS/lib/gcc using the full absolute path to
Emacs.app. If there are obsure characters like "[]" and others in the
absolute path, it can cause glob search within the
native-compile-setup-environment-variables function to fail, in turn
preventing native-comp from working.

The fix is to hard-code the relative paths from Emacs'
invocation-directory (**/Emacs.app/Contents/MacOS) into the environment
setup function itself, making it very simple and effectively just
joining a few strings and setting an environment variable.

It did require a little bit of cleanup and better organization of the
GCC/libgccjit releated code in the build script, creating a new GccInfo
class which is the central place for determining various paths and
information about GCC and libgccjit which the build will be using.

patches/native-comp-env-setup.diff.erb

@@ -0,0 +1,57 @@
+diff --git a/lisp/emacs-lisp/comp.el b/lisp/emacs-lisp/comp.el
+index 4036080976..2ff8dbd74c 100644
+--- a/lisp/emacs-lisp/comp.el
++++ b/lisp/emacs-lisp/comp.el
+@@ -4079,6 +4079,52 @@ of (commands) to run simultaneously."
+   (let ((load (not (not load))))
+     (native--compile-async paths recursively load selector)))
+ 
++;;;###autoload
++(defun native-compile-setup-environment-variables (&rest _args)
++  "Ensure LIBRARY_PATH is set correctly when libgccjit is bundled."
++  (when (and (eq system-type 'darwin)
++             (string-match-p "\.app\/Contents\/MacOS\/?$"
++                             invocation-directory))
++    (let* ((library-path-env (getenv "LIBRARY_PATH"))
++           (devtools-dir
++            "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/lib")
++           (gcc-dir (expand-file-name
++                     "<%= relative_lib_dir %>"
++                     invocation-directory))
++           (darwin-dir (expand-file-name
++                        "<%= relative_darwin_lib_dir %>"
++                        invocation-directory))
++           (lib-paths (list)))
++
++      (if library-path-env
++          (push library-path-env lib-paths))
++      (if (file-directory-p devtools-dir)
++          (push devtools-dir lib-paths))
++      (push darwin-dir lib-paths)
++      (push gcc-dir lib-paths)
++
++      (setenv "LIBRARY_PATH" (mapconcat 'identity lib-paths ":"))))
++
++  ;; Remove advice, as it only needs to run once.
++  (advice-remove 'native-compile
++                 'native-compile-setup-environment-variables)
++  (advice-remove 'comp--native-compile
++                 'native-compile-setup-environment-variables)
++  (advice-remove 'native-compile-async
++                 'native-compile-setup-environment-variables)
++  (advice-remove 'native--compile-async
++                 'native-compile-setup-environment-variables))
++
++;; Ensure environment setup runs before any native compilation.
++(advice-add 'native-compile :before
++            'native-compile-setup-environment-variables)
++(advice-add 'comp--native-compile :before
++            'native-compile-setup-environment-variables)
++(advice-add 'native-compile-async :before
++            'native-compile-setup-environment-variables)
++(advice-add 'native--compile-async :before
++            'native-compile-setup-environment-variables)
++
+ (provide 'comp)
+ 
+ ;;; comp.el ends here