host/include/uhd/types/bye_vector.hpp: include cstdint

[ffontaine]

Include cstdint to fix the following build failure:

In file included from /home/buildroot/instance-0/output-1/build/uhd-4.3.0.0/host/lib/types/byte_vector.cpp:9: /home/buildroot/instance-0/output-1/build/uhd-4.3.0.0/host/include/uhd/types/byte_vector.hpp:19:21: error: 'uint8_t' was not declared in this scope; did you mean 'boost::uint8_t'?
   19 | typedef std::vector<uint8_t> byte_vector_t;
      |                     ^~~~~~~
      |                     boost::uint8_t

Fixes:

• http://autobuild.buildroot.org/results/2cba1535b42e36a62b611af01088622912b277e7

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[mbr0wn]

Thanks @ffontaine. I started playing around with IWYU which will make this PR obsolete, but this inspired me to give IWYU a try.