bitbake.conf/toolchain-shar-extract: Use en_US.UTF-8 as locale
Under python 3, if we spawn python processes, we need to have a UTF-8 locale,
else python's file access methods will use ascii. You can't change that mode
once the interpreter is started so we have to ensure a locale is set. Ideally
we'd use C.UTF-8 since OE already forces the C locale but not all distros support
that and we need to set something so en_US.UTF-8 seems as standard we we can get.
This matches the change in bitbake revision
8902c29638411d312e6fc4a197707e5742652e15
Also set this into the environment used when installing SDKs since
python can be run and we need to ensure we use a standardised locale
which is available from things like buildtools-tarball.
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
