[PATCH] Add -x mode to include/install-sh; add build hints to doc/INSTALL.

[Christoph Hellwig]

Should be two separate patches/commits, please.

It would be useful to mention what package this is again in the
subject line:

	[PATCH] xfsprogs: add -x mode to include/install-sh
	[PATCH] xfsprogs: add build hints to doc/INSTALL

(also note that commit subject lines after the prefix are not
capitalized.

>  	# make install-dev
> +	[and optionally, for the development libraries and full headers;
> +         this is required to build xfstests]
> +	# make install-qa

It's not actually required anymore.