Documented INCLUDE_METAL_SOURCES option for standalone does nothing

[thestr4ng3r]

Documented here:
https://github.com/sifive/freedom-e-sdk/tree/badc53934a495d6d5c8454b9a4d752d8b7e274a5#create-a-standalone-project

But the variable is never used anywhere:

florian-macbook:freedom-e-sdk florian$ grep INCLUDE_METAL_SOURCES -r .
./README.md:make [PROGRAM=hello] [TARGET=sifive-hifive1] [INCLUDE_METAL_SOURCES=1] STANDALONE_DEST=/path/to/desired/location standalone

In particular, the standalone target always unconditionally copies freedom-metal here:

freedom-e-sdk/Makefile

Lines 381 to 382 in badc539

	cp -r freedom-metal $</
	find $</freedom-metal -name ".git*" | xargs rm -rf

or here:

freedom-e-sdk/Makefile

Lines 474 to 475 in badc539

	cp -r freedom-metal $</
	find $</freedom-metal -name ".git*" | xargs rm -rf