Split large sed scripts, for HP-UX sed. * modules/math (Makefile.am): Split sed scripts around 50 sed commands, to avoid HP-UX limit of 99 commands, in the near future. * modules/stdlib (Makefile.am): Likewise. * modules/unistd (Makefile.am): Likewise. * modules/wchar (Makefile.am): Likewise. Reported by Albert Chin <bug-gnulib@mlists.thewrittenword.com>. Suggestion by Ralf Wildenhues <Ralf.Wildenhues@gmx.de> in <http://lists.gnu.org/archive/html/bug-gnulib/2010-01/msg00216.html>.