5 POSIX specification: @url{http://www.opengroup.org/susv3xsh/strdup.html}
9 Portability problems fixed by Gnulib:
12 This function is missing on some old platforms.
14 This function has no prototype in @code{<string.h>} on some old platforms.
17 Portability problems not fixed by Gnulib:
20 Upon failure, the function does not set @code{errno} to @code{ENOMEM} on