macos: tests: use curl of wget is not available

tests/dl-linux-tarball.bash

@@ -3,6 +3,7 @@
 # This script checks the size of /tmp/linux-3.0.tar.gz and downloads
 # a fresh copy if the size is incorrect or the file is missing.
 
+URL=https://cdn.kernel.org/pub/linux/kernel/v3.0/linux-3.0.tar.gz
 TGZ=/tmp/linux-3.0.tar.gz
 
 SIZE_WANT=96675825
@@ -18,6 +19,9 @@ fi
 
 if [[ $SIZE_ACTUAL -ne $SIZE_WANT ]]; then
 	echo "Downloading linux-3.0.tar.gz"
-	wget -nv --show-progress -c -O $TGZ \
-		https://cdn.kernel.org/pub/linux/kernel/v3.0/linux-3.0.tar.gz
+	if command -v wget > /dev/null ; then
+		wget -nv --show-progress -c -O $TGZ $URL
+	else
+		curl -o $TGZ $URL
+	fi
 fi