libcap: Update to version 2.73

libcap: Update to version 2.73

- Update from version 2.72 to 2.73
- Update of rootfile
- This version builds correctly with aarch64 - tested out building on the aarch64-builder
   system
- Changelog
    2.73
	Bug fixes for libpsx changes in the 2.72 release.
	    Some architectures do not support the system call getdents(). More
	     modern architectures only support getdents64(), so use that. Patch
	     provided by Xi Ruoyao.
	    gettid() isn't consistently defined in all *libc's so create a macro
	     for using it in the libpsx sources.
	Fix some static analysis found issues, surfaced by Carlos
	 Rodriguez-Fernandez from an analysis performed on Fedora's libcap-2.71
	 release.
	Third attempt to get an executable cap package runnable example into the
	 documentation on go.pkg.dev.
	    It still isn't working, but I think the issue is now one for the go.dev
	     website:
	    Filed go/issues/70630 which got duped into this go/issues/70611 and
	     a fix was requested by Ian Taylor.
	    Remove a redundant c.String() function since fmt.Println(c) can figure
	     this detail out.
	Freshen up setcap.c sources. Sort the argument help.
	Add go vet to the tests for cap and psx packages.

Signed-off-by: Adolf Belka <adolf.belka@ipfire.org>
Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>