[Dexter] Ignore step information in __libc_start_call_main

The test dexter/feature_tests/commands/perfect/expect_step_kind/direction.cpp
was failing on a machine because __libc_start_call_main was not identified as a
"frame below main" (a frame we don't want to gather information from), causing
dexter to count one more step than expected in the test.

Add __libc_start_call_main to the list of "frames below main". There may
be a more robust way of doing this but this is a pragmatic solution we can
use for now.

cross-project-tests/debuginfo-tests/dexter/dex/debugger/lldb/LLDB.py

@@ -259,7 +259,7 @@ def is_finished(self):
 
     @property
     def frames_below_main(self):
-        return ['__scrt_common_main_seh', '__libc_start_main']
+        return ['__scrt_common_main_seh', '__libc_start_main', '__libc_start_call_main']
 
     def evaluate_expression(self, expression, frame_idx=0) -> ValueIR:
         result = self._thread.GetFrameAtIndex(frame_idx