python3targetconfig.bbclass: use PYTHONPATH to point to the target config

There is no need to patch native python so that it looks in the target
sysroot; the same can be achieved with just an environment variable.

(From OE-Core rev: c9617c03bceee54dc540318cada392799b137bd5)

Signed-off-by: Alexander Kanavin <alex@linutronix.de>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes-recipe/python3targetconfig.bbclass

@@ -12,6 +12,7 @@ DEPENDS:append = " ${EXTRA_PYTHON_DEPENDS}"
 
 setup_target_config() {
         export _PYTHON_SYSCONFIGDATA_NAME="_sysconfigdata"
+        export PYTHONPATH=${STAGING_LIBDIR}/python-sysconfigdata
         export PATH=${STAGING_EXECPREFIXDIR}/python-target-config/:$PATH
 }