libretiny: log nm failure reason instead of silently swallowing

esphome/components/libretiny/patch_linker.py.script

@@ -123,7 +123,8 @@ def _post_link(target, source, env):
         out = subprocess.check_output(
             [nm, "--defined-only", "--demangle", elf], text=True
         )
-    except (OSError, subprocess.CalledProcessError):
+    except (OSError, subprocess.CalledProcessError) as exc:
+        print("ESPHome: IRAM_ATTR summary unavailable (nm failed: {})".format(exc))
         return
     start = end = None
     fallback = []