93fb037d84 introduced unportable shell
syntax, which led to erros like
./configure: 3179: ./configure: CFLAGS+= -D__STDC_WANT_LIB_EXT1__=1: not found
in case a posix shell is used.
Reviewed-By: Christian Heimes <cheimes@redhat.com>
Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>
