Use correct arguments for stat on macOS

code/build.sh

@@ -9,6 +9,13 @@ is_git() {
     return 0
 }
 
+stat_bytes() {
+    case "$(uname -s)" in
+        Darwin) stat -f %z "$1";;
+        *) stat -c %s "$1";;
+    esac
+}
+
 # Script settings
 
 destination=../firmware
@@ -104,7 +111,7 @@ build_environments() {
     for environment in $environments; do
         echo -n "* espurna-$version-$environment.bin --- "
         platformio run --silent --environment $environment || exit 1
-        stat -c %s .pioenvs/$environment/firmware.bin
+        stat_bytes .pioenvs/$environment/firmware.bin
         [[ "${TRAVIS_BUILD_STAGE_NAME}" = "Test" ]] || \
             mv .pioenvs/$environment/firmware.bin $destination/espurna-$version/espurna-$version-$environment.bin
     done