Disable a Darwin test under LSan.

* Changing source lines seems to cause us to hit rdar://problem/62132428.
* Even if I workaround the above issue sometimes the source line in the dylib reported by atos is off by one.

It's simpler to just disable the test for now.

rdar://problem/61793759

compiler-rt/test/sanitizer_common/TestCases/Darwin/print-stack-trace-in-code-loaded-after-fork.cpp

@@ -3,6 +3,8 @@
 // RUN: %env_tool_opts=verbosity=3 %run %t_loader %t_shared_lib.dylib > %t_loader_output.txt 2>&1
 // RUN: FileCheck -input-file=%t_loader_output.txt %s
 // RUN: FileCheck -check-prefix=CHECK-STACKTRACE -input-file=%t_loader_output.txt %s
+// rdar://problem/61793759 and rdar://problem/62126022.
+// UNSUPPORTED: lsan
 
 #include <stdio.h>