MFC r314654:

cddl: normalize paths using SRCTOP-relative paths or :H when possible

This simplifies make logic/output

While here, remove bogus CFLAGS which look for headers in cddl/lib/libumem.
There aren't any source files there (just Makefiles)

MFC r262542:
Move some files that are identical on i386 and amd64 to an x86 subdirectory
rather than keeping duplicate copies.

MFC r262542:
Move some files that are identical on i386 and amd64 to an x86 subdirectory
rather than keeping duplicate copies.