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 -ru ltrace-0.5.3.org/Makefile.in ltrace-0.5.3/Makefile.in

 --- ltrace-0.5.3.org/Makefile.in	2011-08-21 18:55:15.000000000 +0200

 +++ ltrace-0.5.3/Makefile.in	2011-08-21 18:40:53.000000000 +0200

 @@ -39,7 +40,7 @@

  		$(CC) $(LDFLAGS) $^ $(LIBS) -o $@

  libltrace.a: 	sysdeps/sysdep.o $(OBJ)

 -		$(AR) rcv $@ $^

 +		$(AR) rscv $@ $^

  $(OBJ):		sysdeps/sysdep.o