configure: Add macOS-specific debug flags for libbacktrace compatibility

On macOS, libbacktrace was failing to find debug information due to:
1. Debug symbols not being properly linked with dsymutil
2. Apple Clang 17.0.0 generating DWARF 5 which libbacktrace couldn't parse

In this commit we address both issues:

Debug symbol accessibility:
- Add dsymutil integration in Makefile to properly link debug symbols
- Use -fno-standalone-debug to embed debug info inline in executable

DWARF format compatibility:
- Force -gdwarf-4 instead of default DWARF 5 to avoid "DW_FORM_addrx value out of range" errors

Changelog-added: libbacktrace works with macOS

Makefile

@@ -684,12 +684,18 @@ $(ALL_TEST_PROGRAMS) $(ALL_FUZZ_TARGETS): %: %.o
 # (as per EXTERNAL_LDLIBS) so we filter them out here.
 $(ALL_PROGRAMS) $(ALL_TEST_PROGRAMS):
 	@$(call VERBOSE, "ld $@", $(LINK.o) $(filter-out %.a,$^) $(LOADLIBES) $(EXTERNAL_LDLIBS) $(LDLIBS) libccan.a $($(@)_LDLIBS) -o $@)
+ifeq ($(OS),Darwin)
+	@$(call VERBOSE, "dsymutil $@", dsymutil $@)
+endif
 
 # We special case the fuzzing target binaries, as they need to link against libfuzzer,
 # which brings its own main().
 FUZZ_LDFLAGS = -fsanitize=fuzzer
 $(ALL_FUZZ_TARGETS):
 	@$(call VERBOSE, "ld $@", $(LINK.o) $(filter-out %.a,$^) $(LOADLIBES) $(EXTERNAL_LDLIBS) $(LDLIBS) libccan.a $(FUZZ_LDFLAGS) -o $@)
+ifeq ($(OS),Darwin)
+	@$(call VERBOSE, "dsymutil $@", dsymutil $@)
+endif
 
 
 # Everything depends on the CCAN headers, and Makefile

configure

@@ -148,7 +148,18 @@ set_defaults()
     # which matters since you might explicitly set of these blank.
     PREFIX=${PREFIX:-/usr/local}
     CC=${CC:-cc}
-    CDEBUGFLAGS=${CDEBUGFLAGS--std=gnu11 -g -fstack-protector-strong}
+            # Detect macOS and use appropriate debug flags for libbacktrace compatibility
+    if [ "$(uname -s)" = "Darwin" ]; then
+        # Always override to avoid DWARF 5
+        CDEBUGFLAGS="-std=gnu11 -g -gdwarf-4 -fstack-protector-strong"
+
+        # Optional: confirm dsymutil is available
+        if ! command -v dsymutil >/dev/null 2>&1; then
+            echo "Warning: dsymutil not found. Install Xcode Command Line Tools for better debug support."
+        fi
+    else
+        CDEBUGFLAGS=${CDEBUGFLAGS--std=gnu11 -g -fstack-protector-strong}
+    fi
     DEBUGBUILD=${DEBUGBUILD:-0}
     COMPAT=${COMPAT:-1}
     STATIC=${STATIC:-0}
@@ -194,6 +205,9 @@ usage()
     usage_with_default "CWARNFLAGS" "$DEFAULT_CWARNFLAGS"
     usage_with_default "COPTFLAGS" "$DEFAULT_COPTFLAGS"
     usage_with_default "CDEBUGFLAGS" "$CDEBUGFLAGS"
+    if [ "$(uname -s)" = "Darwin" ]; then
+        echo "    Note: On macOS, -g is used instead of -g3 for libbacktrace compatibility"
+    fi
     usage_with_default "CONFIGURATOR_CC" "${CONFIGURATOR_CC:-$CC}"
     echo "    To override compile line for configurator itself"
     usage_with_default "PYTEST" "$PYTEST"