postgresql: Inherit python3targetconfig
it now ends up searching native python shared libraries and tries to
link with it and fails on non-host architectures
recipe-sysroot-native/usr/lib/libpython3.9.so: file not recognized: file format not recognized
collect2: error: ld returned 1 exit status
Signed-off-by: Khem Raj <raj.khem@gmail.com>