Commit 9189a26664 caused llvm-jitlink to create bare JITDylibs to wrap real
dylibs loaded via -preload. This exposed a bug in MachOPlatform where we
assumed that all JITDylibs had been registered with the platform through
MachOPlatform::setupJITDylib (bare JITDylibs are _not_ run through this
function), and errored out where this was not the case.
This bug in MachOPlatform was causing test failures in compilert-rt:
Failed Tests (2):
ORC-x86_64-darwin :: TestCases/Darwin/x86-64/trivial-objc-methods.S
ORC-x86_64-darwin :: TestCases/Darwin/x86-64/trivial-swift-types-section.S
This commit fixes the issue by skipping JITDylibs that haven't been registered
with the platform via MachOPlatform::setupJITDylib.