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>

# libelf config file

choice

    bool

    prompt "libelf version"

# Don't remove next line

# CT_INSERT_VERSION_BELOW

config LIBELF_V_0_8_13

    bool

    prompt "0.8.13"

config LIBELF_V_0_8_12

    bool

    prompt "0.8.12"

endchoice

config LIBELF_VERSION

    string

# Don't remove next line

# CT_INSERT_VERSION_STRING_BELOW

    default "0.8.13" if LIBELF_V_0_8_13

    default "0.8.12" if LIBELF_V_0_8_12