Std 1003.1-2008. Both Linux and Solaris conforms to the new definitions,
so we better follow too (older glibc used old BSDish alphasort prototype
and corresponding type of the comparision function for scandir). While
there, change the definitions of the functions to ANSI C and fix several
style issues nearby.
Remove requirement for "sys/types.h" include for functions from manpage.
POSIX also requires that alphasort(3) sorts as if strcoll(3) was used,
but leave the strcmp(3) call in the function for now.
Adapt in-tree callers of scandir(3) to new declaration. The fact that
select_sections() from catman(1) could modify supplied struct dirent is
a bug.
PR: standards/142255
MFC after: 2 weeks
4176dd5267