jsoncpp: do not always build static library

Currently, static libray is always built as BUILD_STATIC_LIBS is ON by
default so correctly set BUILD_STATIC_LIBS depending on BR2_SHARED_LIBS
variable

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/jsoncpp/jsoncpp.mk

@@ -15,4 +15,10 @@ JSONCPP_CONF_OPTS += \
 	-DJSONCPP_WITH_TESTS=OFF \
 	-DJSONCPP_WITH_STRICT_ISO=OFF
 
+ifeq ($(BR2_SHARED_LIBS),y)
+JSONCPP_CONF_OPTS += -DBUILD_STATIC_LIBS=OFF
+else
+JSONCPP_CONF_OPTS += -DBUILD_STATIC_LIBS=ON
+endif
+
 $(eval $(cmake-package))