Snippets for shadow 4.18.0 from Alpine armv7

Sourced from https://build.alpinelinux.org/buildlogs/build-edge-armv7/community/shadow/shadow-4.18.0-r1.log.

• /usr/include/sys/cdefs.h:4:2: warning: #warning usage of non-standard #include <sys/cdefs.h> is deprecated [-Wcpp]
      4 | #warning usage of non-standard #include <sys/cdefs.h> is deprecated
        |  ^~~~~~~
  

• ./string/strspn/strrspn.h:29:11: warning: assignment discards 'const' qualifier from pointer target type [-Wdiscarded-qualifiers]
     29 |         p = strnul(s);
        |           ^
  

• ./string/strspn/strrcspn.h:29:11: warning: assignment discards 'const' qualifier from pointer target type [-Wdiscarded-qualifiers]
     29 |         p = strnul(s);
        |           ^
  

• ../lib/string/strspn/strrspn.h:29:11: warning: assignment discards 'const' qualifier from pointer target type [-Wdiscarded-qualifiers]
     29 |         p = strnul(s);
        |           ^
  

• faillog.c:184:35: warning: format '%lu' expects argument of type 'long unsigned int', but argument 2 has type 'time_t' {aka 'long long int'} [-Wformat=]
    184 |                         printf (_(" [%lus left]"),
        |                                   ^~~~~~~~~~~~~~