The "bitbake meta-toolchain" comment is dated and incorrect, fix to
point at -c populate_sdk.
If a toolchain contains multiple environment files, iterate them and run
the sdk test suite on each on in turn rather than giving a fatal error and
giving up.
Also improve the debug output so that rather than PN, it also show the
toolchain tarball under test, and the environment file name its using.
Also enable the accidentally disabled cleanup code.
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
