alsa-lib: check if wordexp is supported in libc

alsa-lib: check if wordexp is supported in libc

eglibc could be configured to build without the wordexp feature.  To
ensure that the wordexp feature could be used, the configure script must
check if wordexp() is supported in libc in addition to checking if
wordexp.h exists.

(From OE-Core rev: 3c3fe1d139fc84d7ff125f87a4692fac6dfc04e6)

Signed-off-by: Hong H. Pham <hong.pham@windriver.com>
Signed-off-by: Jesse Zhang <sen.zhang@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>