Make fuchsia-test-runner.py compatible with new JSON output from llvm-readelf

[A recent commit in LLVM](llvm/llvm-project@ab930ee) modified the JSON output of LLVM. The LLVM change renamed "Notes" to "NoteSections" and inserted a new "Notes" key nested under each "NoteSection".

This change shores up exceptions around reading the JSON output of llvm-readelf and reads from "NoteSections" instead of the non-existent "Notes".

Author: c6c7

src/ci/docker/scripts/fuchsia-test-runner.py

@@ -193,18 +193,34 @@ def build_id(self, binary):
             stderr=subprocess.STDOUT,
         )
         if process.returncode:
-            self.env_logger.error(
-                f"llvm-readelf failed for binary {binary} with output {process.stdout}"
+            e = f"llvm-readelf failed for binary {binary} with output {process.stdout}"
+            self.env_logger.error(e)
+            raise Exception(e)
+
+        elf_output = json.loads(process.stdout)
+        if len(elf_output) != 1:
+            raise Exception(
+                f"JSON returned by llvm-readelf for binary {binary} is not a list with a single entry"
             )
-            raise Exception(f"Unreadable build-id for binary {binary}")
-        data = json.loads(process.stdout)
-        if len(data) != 1:
-            raise Exception(f"Unreadable output from llvm-readelf for binary {binary}")
-        notes = data[0]["Notes"]
-        for note in notes:
-            note_section = note["NoteSection"]
-            if note_section["Name"] == ".note.gnu.build-id":
-                return note_section["Note"]["Build ID"]
+
+        try:
+            note_sections = elf_output[0]["NoteSections"]
+        except KeyError as e:
+            e.add_note(
+                f'Failed to read "NoteSections" from llvm-readelf for binary {binary}'
+            )
+            raise
+    
+        for entry in note_sections:
+            try:
+                note_section = entry["NoteSection"]
+                if note_section["Name"] == ".note.gnu.build-id":
+                    return note_section["Note"]["Build ID"]
+            except KeyError as e:
+                e.add_note(
+                    f'Failed to read ".note.gnu.build-id" from NoteSections entry in llvm-readelf for binary {binary}'
+                )
+                raise
         raise Exception(f"Build ID not found for binary {binary}")
 
     def generate_buildid_dir(