lib: clean up build files

lib: clean up build files

Switch from using tabs to 4 spaces for meson.build indentation. Perform
other formatting cleanups such as ensure that long lists of files are one
per line, and terminating with a final comma before the closing brace to
make addition/removals easier. In some cases, reorder lists of items
where they were not in alphabetical order.

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>