[MachO] Don't fold compact unwind entries with LSDA

Folding them will cause the unwinder to compute the incorrect function
start address for the folded entries, which in turn will cause the
personality function to interpret the LSDA incorrectly and break
exception handling.

You can verify the end-to-end flow by creating a simple C++ file:
```
void h();
int main() { h(); }
```

and then linking this file against the liblsda.dylib produced by the
test case added here. Before this change, running the resulting program
would result in a program termination with an uncaught exception.
Afterwards, it works correctly.

Reviewed By: #lld-macho, thevinster

Differential Revision: https://reviews.llvm.org/D132845

(cherry picked from commit 56bd3185)