use -MMD if the compiler supports it

it's better than the previous Makefile.depend approach since this
automatically adapts to the included headers without requiring
manual intervention to regen the list.

1 files changed, 4 insertions, 0 deletions

diff --git a/configure b/configure
index c7a1609..adb662d 100755
--- a/configure
+++ b/configure
@@ -240,6 +240,10 @@ fi
 # --------
 # tests for config.h
 
+if runtest noop MMD -MMD; then
+	CFLAGS="${CFLAGS} -MMD"
+fi
+
 runtest err		ERR		|| true
 runtest explicit_bzero	EXPLICIT_BZERO	|| true
 runtest freezero	FREEZERO	|| true