What @frostschutz said, plus the triplet variable should be called CROSS_TC, not CROSS_COMPILE, and should *not* contain the trailing dash (because this is tailored for my own TCs).
You'll probably indeed need to enforce -std=gnu11 with GCC 4.9, as that's the minimum requirement

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I'll try to silence those pragma warnings, since disabling an option that doesn't exist yet is pretty harmless

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I do have a 4.9 TC laying around, I'll take a look later tonight.