Fix parsing of -b option with OPTARG

Follow-up to #2.

Author: akien-mga

build-release.sh

@@ -26,7 +26,7 @@ godot_version=""
 build_classical=1
 build_mono=1
 
-while getopts "h?v:b" opt; do
+while getopts "h?v:b:" opt; do
   case "$opt" in
   h|\?)
     echo "Usage: $0 [OPTIONS...]"

build-templates.sh

@@ -7,7 +7,7 @@ templates_version=""
 build_classical=1
 build_mono=1
 
-while getopts "h?v:t:b" opt; do
+while getopts "h?v:t:b:" opt; do
   case "$opt" in
   h|\?)
     echo "Usage: $0 [OPTIONS...]"