build-unit-test-docker: Add doxygen

Doxygen can be used to build libpldm's documentation. Add it to the
container image so issues with doxygen comments can be caught once we've
cleaned up the warnings.

Change-Id: I2c5e043cc7ba85eb5ed7da293e3a73203dabd089
Signed-off-by: Andrew Jeffery <andrew@codeconstruct.com.au>
1 file changed