python,python3: Increase max recursion level when generating bytecode

python,python3: Increase max recursion level when generating bytecode

"python -m compileall" has a default maximum recursion level of 10, i.e.
it will descend up to 10 levels of subdirectories when looking for
source files to compile. This is usually sufficient but there are
packages that include more than 10 levels (botocore,
https://github.com/openwrt/packages/pull/8214#discussion_r270056741).

This adds the "-r" command line option to the call to compileall to
increase the max recursion level (currently set to 20).

This also patches Python 2's compileall.py to add this max recursion
level option. (Python 3's compileall.py already supports this option.)

This also applies some related changes to python-package-install.sh:

* Use the "-delete" option with find instead of exec'ing rm / rmdir. For
  the case of removing empty directories (in delete_empty_dirs()), this
  has the added benefit of simplifying the code, as the "-delete" option
  implies "-depth", and thus find "does the right thing" (removing empty
  directories depth-first).

* Remove the backslash in "-name" patterns (for find), as they are not
  regular expression but glob patterns.

Signed-off-by: Jeffery To <redacted>