[lldb][lit] Add MallocNanoZone envvar to Darwin ASan builds (#88431)

When builds on Darwin are configured with ASan, running tests will emit
a warning about malloc's nano zone (`malloc: nano zone abandoned due to inability to reserve vm space`) that can interfere with the test
output and cause failures. Setting the environment variable
`MallocNanoZone` to 0 will remove this warning and allow the tests to
run as normal.

Author: chelcassanova

lldb/test/API/lit.cfg.py

@@ -121,6 +121,7 @@ def delete_module_cache(path):
             config.environment["DYLD_INSERT_LIBRARIES"] = find_sanitizer_runtime(
                 "libclang_rt.asan_osx_dynamic.dylib"
             )
+            config.environment["MallocNanoZone"] = "0"
 
     if "Thread" in config.llvm_use_sanitizer:
         config.environment["TSAN_OPTIONS"] = "halt_on_error=1"

lldb/test/Shell/lit.cfg.py

@@ -52,6 +52,8 @@
 # Enable sanitizer runtime flags.
 config.environment["ASAN_OPTIONS"] = "detect_stack_use_after_return=1"
 config.environment["TSAN_OPTIONS"] = "halt_on_error=1"
+if "Darwin" in config.host_os:
+    config.environment["MallocNanoZone"] = "0"
 
 # Support running the test suite under the lldb-repro wrapper. This makes it
 # possible to capture a test suite run and then rerun all the test from the