Source: tbb Version: 4.3~20150611-2 Severity: normal The package description says: (Note: if you are a user of the i386 architecture, i.e., 32-bit Intel or compatible hardware, this package only supports Pentium4-compatible and higher processors.)
Looking at debian/patches/buildi386.patch and buildd logs this seems to no longer be true. debian/patches/buildi386.patch sets -march=i586, which is below the 686 minimum in stretch. It shouldn't set anything for -march and use whatever is default.