BUILD: Make DEBUG part of .build_opts
This forces a recompilation if the value of DEBUG= changes.
diff --git a/Makefile b/Makefile
index b93b0a8..ff2084d 100644
--- a/Makefile
+++ b/Makefile
@@ -878,7 +878,7 @@
# Used only to force a rebuild if some build options change, but we don't do
# it for certain targets which take no build options
ifneq (reg-tests, $(firstword $(MAKECMDGOALS)))
-build_opts = $(shell rm -f .build_opts.new; echo \'$(TARGET) $(BUILD_OPTIONS) $(VERBOSE_CFLAGS)\' > .build_opts.new; if cmp -s .build_opts .build_opts.new; then rm -f .build_opts.new; else mv -f .build_opts.new .build_opts; fi)
+build_opts = $(shell rm -f .build_opts.new; echo \'$(TARGET) $(BUILD_OPTIONS) $(VERBOSE_CFLAGS) $(DEBUG)\' > .build_opts.new; if cmp -s .build_opts .build_opts.new; then rm -f .build_opts.new; else mv -f .build_opts.new .build_opts; fi)
.build_opts: $(build_opts)
else
.build_opts: