[Meta bug] GNU testsuite

[sylvestre]

The goal of this meta bug is to reference all GNU tests failing and what we need to fix them.

• Get remaining GNU test cases from ERROR to at least FAIL #3320
• cp-parents.sh: cp: recursive copy #3332
• all: return code for invalid options #3331
• all: print format of invalid option #3333
• GNU tests factor regressions #3171
• dir and vdir are missing #3163
• chmod: passing multiple modes with leading hyphens. #3147
• cksum: failing GNU tests #2930
• mv/i-5.sh: interactive question isn't prompted #3337
• Implement ls --group-directories-first #3519

[sylvestre]

We moved to project mgmt for this:
GNU Compatibility