guile: fix a bashism

guile: fix a bashism

A following flaw was detected by verify-bashisms script:
......
meta/recipes-devtools/guile/guile_2.0.13.bb
possible bashism in guile_cross_config line 94 ($'...' should be "$(printf '...')"):

   echo '#!'`which ${BUILD_SYS}-guile`$' \\\n--no-auto-compile -e main -s\n!#\n(define %guile-build-info '\'\( \
       > ${B}/guile-config.cross
......

Fixed by removing $'...' from echo command, using a printf instead.

Signed-off-by: Ming Liu <peter.x.liu@external.atlascopco.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>