all: fix wildcard to work with make-4.x

In make-3.8x, the $(wildacrd) function would sort the entries,
while in make-4.x, it would just return the entries in any
unpredictable order [*]

Use the $(sort) function to get reproducible behaviour.

[*] Well, most probably the roder the entries appear when read
from readdir()

Reported-by: Andrew Ruder <andrew.ruder@elecsyscorp.com>
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Tested-by: Andrew Ruder <andrew.ruder@elecsyscorp.com>

 diff -urN glibc-2.10.1-orig/manual/Makefile glibc-2.10.1/manual/Makefile

 --- glibc-2.10.1-orig/manual/Makefile 2006-01-07 22:43:47.000000000 -0800

 +++ glibc-2.10.1/manual/Makefile 2014-01-15 11:49:08.256982014 -0800

 @@ -232,7 +232,11 @@

  .PHONY: stubs

  stubs: $(objpfx)stubs

  endif

 -$(objpfx)stubs ../po/manual.pot $(objpfx)stamp%:

 +$(objpfx)stamp%:

 +	$(make-target-directory)

 +	touch $@

 +

 +$(objpfx)stubs ../po/manual.pot:

  	$(make-target-directory)

  	touch $@