use AM_YFLAGS since YFLAGS is a user variable

diff --git a/Makefile.am b/Makefile.am
index 9ac24ff38a614acfd9b1586cf0388a50429a2c3c..0be229eda86f2a6ea19e587cbb9d46aca9750637 100644 (file)
--- a/Makefile.am
+++ b/Makefile.am
@@ -33,7 +33,7 @@
 # For MS-DOS, add "-DMS_DOS" to DEFS.  See the directory MISC/MSDOS for
 # additional info.
 
-YFLAGS = -d
+AM_YFLAGS = -d
 ACLOCAL_AMFLAGS = -I m4
 help2man = @HELP2MAN@
 m4 = @M4@