darwin: Fix sysroot on simulator

[ChiChou]

The patch for frida/frida#2763

frida has stoppped working on iOS simulators for months, getting module not found at "/usr/lib/libSystem.B.dylib" error. The root cause is the logic for getting sysroot stops working.

Had some discussion with @mrmacete yesterday at 0x41con. We talked about reading env remotely, but surprisingly found the current implementation has a cheat to simply detect the location of dyld_sim. However the assumtion that dyld_sim is the first loaded image is no longer true. We need one more loop to initialize sysroot before putting them to the lookup table.

Also I believe this is the correct patch for frida/frida-swift-bridge#18

Kudos to Francesco for helping me to set up the latest env and understand the source! 🙌

[ChiChou]

This pull request has no test code yet. I wonder if it's possible for the CI to run the simulator..

[ChiChou]

Note that the module lookup logic is still problematic under other cases. Here are 2 examples:

1. On macOS, turn off SIP and attach to WhatsApp Latest WhatsApp app seems working
2. Some jailbreak users reported that it happens to their iOS too Issue attaching to iPhone 15 Simulator processes  frida#2763 (comment)

They both throw the following exception, but the root cause should be different.

module not found at "/usr/lib/libSystem.B.dylib"

[oleavr]

Ooh, great catch! Thanks! 🙌