Fix pattern matching to check for Mac target

[armorshard1]

In bash, if [ ... ] does not support pattern matching, so we have to use bash-specific double square brackets.

As an example, the following program will print no match:

#!/bin/bash

COMPILE_TARGET="mac-arm64"

if [ "$COMPILE_TARGET" == "mac-"* ]; then
	echo "match"
else
	echo "no match"
fi

But if we change it to if [[ "$COMPILE_TARGET" == "mac-"* ]] it works as expected.

I found this bug with the shellcheck program