[FS#483] buildbot: lots of packages fail on several platforms due to "C compiler cannot create executables"

[LEDE Bugs]

The following task has a new comment added:

FS#483 - buildbot: lots of packages fail on several platforms due to "C compiler cannot create executables"
User who did this - Jo-Philipp Wich (jow-)

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This is a cascading failure triggered by https://git.lede-project.org/?p=source.git;a=commit;h=f55c29e4c74353ef0795eb83911c708c6db90466

The linked commit failed to adjust the SDK packaging, leading to the generation of SDKs having no toolchain which are then consumed by the phase2 builders.

Will prepare a fix and trigger a global cleanup.
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More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=483#comment1656