package/{pkg-generic, python, python3}: rename .py file exclusion variable to not conflict

Fixes:
http://autobuild.buildroot.net/results/3b6/3b6280b0b7a9634b747db2865b21c6266007c725/

The PYTHON_KEEP_PY_FILES global variable conflicts with the per-package
<pkg>_KEEP_PY_FILES variable for the python package, causing make to
complain:

package/zlib/zlib.mk:7: *** Recursive variable 'PYTHON_KEEP_PY_FILES' references itself (eventually).  Stop.

As a workaround, rename the global variable to KEEP_PYTHON_PY_FILES so it
cannot conflict with the per-package variable.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/pkg-generic.mk

@@ -1060,7 +1060,7 @@ PACKAGES_USERS += $$($(2)_USERS)$$(sep)
 endif
 TARGET_FINALIZE_HOOKS += $$($(2)_TARGET_FINALIZE_HOOKS)
 ROOTFS_PRE_CMD_HOOKS += $$($(2)_ROOTFS_PRE_CMD_HOOKS)
-PYTHON_KEEP_PY_FILES += $$($(2)_KEEP_PY_FILES)
+KEEP_PYTHON_PY_FILES += $$($(2)_KEEP_PY_FILES)
 
 ifeq ($$($(2)_SITE_METHOD),svn)
 DL_TOOLS_DEPENDENCIES += svn

package/python/python.mk

@@ -268,7 +268,7 @@ endif
 ifeq ($(BR2_PACKAGE_PYTHON_PYC_ONLY),y)
 define PYTHON_REMOVE_PY_FILES
 	find $(TARGET_DIR)/usr/lib/python$(PYTHON_VERSION_MAJOR) -name '*.py' \
-		$(if $(strip $(PYTHON_KEEP_PY_FILES)),-not \( $(call finddirclauses,$(TARGET_DIR),$(PYTHON_KEEP_PY_FILES)) \) ) \
+		$(if $(strip $(KEEP_PYTHON_PY_FILES)),-not \( $(call finddirclauses,$(TARGET_DIR),$(KEEP_PYTHON_PY_FILES)) \) ) \
 		-print0 | \
 		xargs -0 --no-run-if-empty rm -f
 endef

package/python3/python3.mk

@@ -286,7 +286,7 @@ endif
 ifeq ($(BR2_PACKAGE_PYTHON3_PYC_ONLY),y)
 define PYTHON3_REMOVE_PY_FILES
 	find $(TARGET_DIR)/usr/lib/python$(PYTHON3_VERSION_MAJOR) -name '*.py' \
-		$(if $(strip $(PYTHON_KEEP_PY_FILES)),-not \( $(call finddirclauses,$(TARGET_DIR),$(PYTHON_KEEP_PY_FILES)) \) ) \
+		$(if $(strip $(KEEP_PYTHON_PY_FILES)),-not \( $(call finddirclauses,$(TARGET_DIR),$(KEEP_PYTHON_PY_FILES)) \) ) \
 		-print0 | \
 		xargs -0 --no-run-if-empty rm -f
 endef