The LC_SUB_FRAMEWORK, LC_SUB_UMBRELLA, LC_SUB_CLIENT, and LC_SUB_LIBRARY
are used to indicate related libraries, binaries or framework names.
Their only payload is the string with the name of the object. Adding
those commands to the list of ignored/skipped load commands will avoid
an error that stop the process of copying/stripping and will copy their
contents verbatim.
Additionally, in order to have a test for this case, `yaml2obj` now
allows those four commands to contain a `Content`.
Differential Revision: https://reviews.llvm.org/D106412
Daniel Rodríguez Troitiño