test-nss: allow the module and names/addresses to be specified (#4258)

Useful for testing a single module. If nothing is specified, behaviour is the
same as before.

$ ./test-nss myhostname 192.168.0.14 localhost
======== myhostname ========
_nss_myhostname_gethostbyname4_r("localhost") → status=NSS_STATUS_SUCCESS
                   pat=buffer+0x38 errno=0/--- h_errno=0/Resolver Error 0 (no error) ttl=0
        "localhost" AF_INET 127.0.0.1 %lo
        "localhost" AF_INET6 ::1 %lo

_nss_myhostname_gethostbyname3_r("localhost", AF_INET) → status=NSS_STATUS_SUCCESS
                   errno=0/--- h_errno=0/Resolver Error 0 (no error) ttl=0
        "localhost"
        AF_INET 127.0.0.1
        canonical: "localhost"

_nss_myhostname_gethostbyname3_r("localhost", AF_INET6) → status=NSS_STATUS_SUCCESS
                   errno=0/--- h_errno=0/Resolver Error 0 (no error) ttl=0
        "localhost"
        AF_INET6 ::1
        canonical: "localhost"

_nss_myhostname_gethostbyname3_r("localhost", *) → status=NSS_STATUS_SUCCESS
                   errno=0/--- h_errno=0/Resolver Error 0 (no error) ttl=0
        "localhost"
        AF_INET 127.0.0.1
        canonical: "localhost"

_nss_myhostname_gethostbyname3_r("localhost", AF_UNIX) → status=NSS_STATUS_UNAVAIL
                   errno=97/EAFNOSUPPORT h_errno=4/No address associated with name ttl=2147483647

_nss_myhostname_gethostbyname2_r("localhost", AF_INET) → status=NSS_STATUS_SUCCESS
                   errno=0/--- h_errno=0/Resolver Error 0 (no error)
        "localhost"
        AF_INET 127.0.0.1

_nss_myhostname_gethostbyname2_r("localhost", AF_INET6) → status=NSS_STATUS_SUCCESS
                   errno=0/--- h_errno=0/Resolver Error 0 (no error)
        "localhost"
        AF_INET6 ::1

_nss_myhostname_gethostbyname2_r("localhost", *) → status=NSS_STATUS_SUCCESS
                   errno=0/--- h_errno=0/Resolver Error 0 (no error)
        "localhost"
        AF_INET 127.0.0.1

_nss_myhostname_gethostbyname2_r("localhost", AF_UNIX) → status=NSS_STATUS_UNAVAIL
                   errno=97/EAFNOSUPPORT h_errno=4/No address associated with name

_nss_myhostname_gethostbyname_r("localhost") → status=NSS_STATUS_SUCCESS
                   errno=0/--- h_errno=0/Resolver Error 0 (no error)
        "localhost"
        AF_INET 127.0.0.1

_nss_myhostname_gethostbyaddr2_r("192.168.0.14") → status=NSS_STATUS_SUCCESS
                   errno=0/--- h_errno=0/Resolver Error 0 (no error) ttl=0
        "laptop"
        AF_INET 192.168.0.14
        AF_INET 192.168.122.1
        AF_INET 169.254.209.76

_nss_myhostname_gethostbyaddr_r("192.168.0.14") → status=NSS_STATUS_SUCCESS
                   errno=0/--- h_errno=0/Resolver Error 0 (no error)
        "laptop"
        AF_INET 192.168.0.14
        AF_INET 192.168.122.1
        AF_INET 169.254.209.76