dropbear: add extra build customization options

v2: only offer option to disable building SSH client.
    do not offer options to disable password authentication and TCP forwarding.

Signed-off-by: Floris Bos <bos@je-eigen-domein.nl>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/dropbear/Config.in

@@ -8,6 +8,16 @@ config BR2_PACKAGE_DROPBEAR
 
 if BR2_PACKAGE_DROPBEAR
 
+config BR2_PACKAGE_DROPBEAR_CLIENT
+	bool "client programs"
+	default y
+	help
+	  Provides the programs: dbclient, ssh
+
+	  Note that the following programs are also used server-side
+	  and are therefore always build regardless this setting:
+	  dropbear, dropbearkey, dropbearconvert, scp
+
 config BR2_PACKAGE_DROPBEAR_DISABLE_REVERSEDNS
 	bool "disable reverse DNS lookups"
 	help

package/dropbear/dropbear.mk

@@ -7,13 +7,20 @@
 DROPBEAR_VERSION = 2015.67
 DROPBEAR_SITE = http://matt.ucc.asn.au/dropbear/releases
 DROPBEAR_SOURCE = dropbear-$(DROPBEAR_VERSION).tar.bz2
-DROPBEAR_TARGET_BINS = dbclient dropbearkey dropbearconvert scp ssh
-DROPBEAR_MAKE = \
-	$(MAKE) MULTI=1 SCPPROGRESS=1 \
-	PROGRAMS="dropbear dbclient dropbearkey dropbearconvert scp"
-
 DROPBEAR_LICENSE = MIT, BSD-2c-like, BSD-2c
 DROPBEAR_LICENSE_FILES = LICENSE
+DROPBEAR_TARGET_BINS = dropbearkey dropbearconvert scp
+DROPBEAR_PROGRAMS = dropbear $(DROPBEAR_TARGET_BINS)
+
+ifeq ($(BR2_PACKAGE_DROPBEAR_CLIENT),y)
+# Build dbclient, and create a convenience symlink named ssh
+DROPBEAR_PROGRAMS += dbclient
+DROPBEAR_TARGET_BINS += dbclient ssh
+endif
+
+DROPBEAR_MAKE = \
+	$(MAKE) MULTI=1 SCPPROGRESS=1 \
+	PROGRAMS="$(DROPBEAR_PROGRAMS)"
 
 ifeq ($(BR2_STATIC_LIBS),y)
 DROPBEAR_MAKE += STATIC=1