build: don't redefine AM_CPPFLAGS in libdane/Makefile.am

Signed-off-by: Daiki Ueno <ueno@gnu.org>

diff --git a/libdane/Makefile.am b/libdane/Makefile.am
index 257271df2c53418ad2e9bbfad204948dc79a302e..493bf9f80d026dd852cacaa7c7255309d9d4c5ab 100644 (file)
--- a/libdane/Makefile.am
+++ b/libdane/Makefile.am
@@ -22,7 +22,7 @@ ACLOCAL_AMFLAGS = -I ../m4 -I ../gl/m4
 
 include $(top_srcdir)/lib/common.mk
 
-AM_CPPFLAGS = \
+AM_CPPFLAGS += \
        -I$(srcdir)/../gl               \
        -I$(builddir)/../gl             \
        -I$(builddir)/../lib/includes   \