Bug#1002968: tbb: cmake support missing on ports architectures

[Aurelien Jarno]

Source: tbb
Version: 2020.3-1
Severity: important
User: debian-riscv at lists.debian.org
Usertags: riscv64

libtbb-dev only provides cmake files on official architectures, due to
this entry in debian/control:

| Build-Depends: debhelper-compat (= 12),
|                libjs-jquery,
|                dh-exec,
|                gdb,
|                cmake [amd64 i386 arm64 armhf mips64el mipsel ppc64el s390x],

This causes some packages build-depending on libtbb-dev to fail to build
from sources on architectures not in the above list:
https://buildd.debian.org/status/fetch.php?pkg=slic3r-prusa&arch=riscv64&ver=2.4.0%2Bdfsg-1&stamp=1640971630&raw=0

Therefore, could you please drop the architectures list from the
Build-Depends, as it is available on all architectures, including ports
ones?

Thanks,
Aurelien