python3: Fix do_configure check platform triplet error (2)

python3: Fix do_configure check platform triplet error (2)

When building for powerpc 32bit with musl following error triggered
from do_configure:

checking for the platform triplet based on compiler characteristics... powerpc-linux-gnu
configure: error: internal configure error for the platform triplet, please file a bug report

This is caused by PLATFORM_TRIPLET != MULTIARCH mismatch since MULTIARCH
in case of musl is powerpc-linux-musl. Since triplet is used as part
module name as described in PEP-3149 to make fix less intrusive alias
powerpc-linux-musl to powerpc-linux-gnu to avoid possible runtime
(e.g. tests) incompatibilities later.

Fix was inspired by commit cda0ef61d373 ("python3: fix do_configure
check platform triplet error").

(From OE-Core rev: b2ec91e12088afa0560aecede587d0970fc64110)

Signed-off-by: Serhey Popovych <serhe.popovych@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>