[Buildroot] [RFC 2/4] genimage.sh: fix getopts traces

[Etienne Phelip]

The first trace is never displayed, the second shows an empty string
because OPTARG is not set.

To display both traces properly, the optstring of getopts needs to
start with a colon.

Signed-off-by: Etienne Phelip <etienne.phelip at savoirfairelinux.com>
---
 support/scripts/genimage.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/support/scripts/genimage.sh b/support/scripts/genimage.sh
index 6684e73..6f9102c 100755
--- a/support/scripts/genimage.sh
+++ b/support/scripts/genimage.sh
@@ -10,7 +10,7 @@ GENIMAGE_TMP="${BUILD_DIR}/genimage.tmp"
 # First argument is BINARIES_DIR, skip it
 shift
 
-while getopts c: OPT ; do
+while getopts :c: OPT ; do
 	case "${OPT}" in
 	c) GENIMAGE_CFG="${OPTARG}";;
 	:) die "option '${OPTARG}' expects a mandatory argument\n";;
-- 
2.9.3