Fixed:
* python3 has introduced _PYTHON_PROJECT_BASE which is used for separate
B and S, but it doesn't work when compile Modules, the target python3 runs
python3-native's sysconfig to get srcdir which is the native's, there
would be errors when native's srcdir has been removed, add
_PYTHON_PROJECT_SRC to fix the problem.
* Check cross_compiling when get FLAGS
Signed-off-by: Robert Yang <liezhi.yang@windriver.com>
