dropwatch: adjust LDFLAGS

Add more library links into LDFLAGS.
-lncurses because readline uses it (missing _tputs and others).
-lpthread for missing _pthread_rwlock_unlock and others.
-lm for missing _rint.
Fixes:
http://autobuild.buildroot.net/results/6b1/6b1f4f2167d8aca0d73dc0e66fd2e1704c821c61/

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/dropwatch/dropwatch.mk

@@ -16,7 +16,8 @@ DROPWATCH_LICENSE_FILES = COPYING
 #
 # Also: always need to add -liberty to hardcoded LDFLAGS for avr32
 DROPWATCH_LDFLAGS = \
-	$(TARGET_LDFLAGS) -lbfd -liberty -lreadline -lnl-3 -lnl-genl-3
+	$(TARGET_LDFLAGS) -lbfd -liberty -lreadline -lnl-3 -lnl-genl-3 \
+		-lpthread -lncurses -lm
 
 ifeq ($(BR2_NEEDS_GETTEXT_IF_LOCALE),y)
 DROPWATCH_LDFLAGS += -lintl