Change bash scripts to be POSIX-compatible

some Unix-like operating systems, namely Alpine, don't come with bash
preinstalled.
scripts in the lib-src/ directory were left untouched.

Signed-off-by: Sol Fisher Romanoff <sol@solfisher.com>

scripts/ci/macos/repeat_hdiutil.sh

@@ -1,4 +1,4 @@
-#!/usr/bin/env bash
+#!/bin/sh
 
 ((${BASH_VERSION%%.*} >= 4)) || { echo >&2 "$0: Error: Please upgrade Bash."; exit 1; }
 
@@ -8,7 +8,7 @@ max_retry=12
 counter=0
 num_secs_await_retry=20
 
-echo "Trying: /usr/bin/hdiutil $@"
+echo "Trying: /usr/bin/hdiutil $*"
 
 until /usr/bin/hdiutil "$@"; do
    sleep $num_secs_await_retry