selftests/nolibc: fix testcase status alignment

Center-align all possible status reports.
Before OK and FAIL were center-aligned in relation to each other but
SKIPPED and FAILED would be left-aligned.

Before:

7 environ_addr = <0x7fffef3e7c50>                                [OK]
8 environ_envp = <0x7fffef3e7c58>                               [FAIL]
9 environ_auxv                                                  [SKIPPED]
10 environ_total                                                [SKIPPED]
11 environ_HOME = <0x7fffef3e99bd>                               [OK]
12 auxv_addr                                                    [SKIPPED]
13 auxv_AT_UID = 1000                                            [OK]

After:

7 environ_addr = <0x7ffff13b00a0>                                 [OK]
8 environ_envp = <0x7ffff13b00a8>                                [FAIL]
9 environ_auxv                                                  [SKIPPED]
10 environ_total                                                [SKIPPED]
11 environ_HOME = <0x7ffff13b19bd>                                [OK]
12 auxv_addr                                                    [SKIPPED]
13 auxv_AT_UID = 1000                                             [OK]

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>