[Buildroot] [PATCH] Makefile: fix Python 3 site packages when using PYC_ONLY

[Philippe Proulx <eeppeliteloop@gmail.com>]

The Python 3 standard lib is compiled into PYC bytecode using a
pre-PEP-3147 mode (.pyc files beside .py files; no __pycache__)
when BR2_PACKAGE_PYTHON3_PYC_ONLY is enabled. However, site packages
installed with setuptools/distutils are compiled following PEP-3147.
When BR2_PACKAGE_PYTHON3_PYC_ONLY is on, .py source files are removed
and Python 3 (target) will not look into __pycache__ directories
without associated .py files.

Python 2 does not suffer from this since PEP-3147 seems to be
implemented in Python 3 only.

This commit fixes this by compiling Python 3 site packages using a
pre-PEP-3147 mode after they are installed and then removing
__pycache__ directories.

Signed-off-by: Philippe Proulx <eeppeliteloop@gmail.com>
---
 Makefile | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/Makefile b/Makefile
index 6bd18e3..b38ccd9 100644
--- a/Makefile
+++ b/Makefile
@@ -574,7 +574,15 @@ ifeq ($(BR2_PACKAGE_PYTHON_PY_ONLY)$(BR2_PACKAGE_PYTHON3_PY_ONLY),y)
 	find $(TARGET_DIR)/usr/lib/ -name '*.pyc' -print0 | xargs -0 rm -f
 endif
 ifeq ($(BR2_PACKAGE_PYTHON_PYC_ONLY)$(BR2_PACKAGE_PYTHON3_PYC_ONLY),y)
+ifeq ($(BR2_PACKAGE_PYTHON3),y)
+	for sp in $(TARGET_DIR)/usr/lib/python3*/site-packages; do \
+		$(HOST_DIR)/usr/bin/python -m compileall -b $$sp; \
+	done
+endif
 	find $(TARGET_DIR)/usr/lib/ -name '*.py' -print0 | xargs -0 rm -f
+ifeq ($(BR2_PACKAGE_PYTHON3),y)
+	find $(TARGET_DIR)/usr/lib/python3* -name __pycache__ -type d -print0 | xargs -0 rm -rf
+endif
 endif
 	rm -rf $(TARGET_DIR)/usr/lib/luarocks
 	rm -rf $(TARGET_DIR)/usr/lib/perl5/$(PERL_VERSION)/pod
-- 
2.0.2