python*native.bbclass: suppress user site dirs

Currently, $HOME/.local is being added into sys.path for the native
Python, causing subtle host contamination. Suppress this by exporting
PYTHONNOUSERSITE = "1" as documented in PEP 370.

(From OE-Core rev: 8fe9fb4d5a61dcbcb3fc5b9ee0234cc135af873f)

Signed-off-by: Martin Kelly <mkelly@xevo.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/python3native.bbclass

@@ -9,5 +9,8 @@ DEPENDS_append = " ${PYTHON_PN}-native "
 export STAGING_INCDIR
 export STAGING_LIBDIR
 
+# suppress host user's site-packages dirs.
+export PYTHONNOUSERSITE = "1"
+
 # autoconf macros will use their internal default preference otherwise
 export PYTHON

meta/classes/pythonnative.bbclass

@@ -12,5 +12,8 @@ DEPENDS_append = " ${PYTHON_PN}-native "
 export STAGING_INCDIR
 export STAGING_LIBDIR
 
+# suppress host user's site-packages dirs.
+export PYTHONNOUSERSITE = "1"
+
 # autoconf macros will use their internal default preference otherwise
 export PYTHON