Linux uapi headers use __packed as an abbreviation for
__attribute__((__packed__)). In the upstream kernel headers this
is defined in linux/compiler_attributes.h, but it is not defined
in the uapi headers. Bionic defines it in sys/cdefs.h, which will
almost always provide the needed definition, but there are uapi
headers that use __packed and do not include any system headers
that would include sys/cdefs.h. Musl's sys/cdefs.h does not
define __packed, which leads to linker errors when __packed is
treated as a variable name.
Replace __packed with __attribute__((__packed__)) when importing
uapi headers to break the dependency on sys/cdefs.h.
Test: m USE_HOST_MUSL=true on oriole-userdebug in internal master
Change-Id: I45f80f4e5aec868b80ce8eb9d757a3e08ae3e1a9