package/lensfun: fix static only build

Build lensfun.a for static only build.

Fixes:
http://autobuild.buildroot.net/results/63e/63e7700a242c7c28ede0fe0b6a63db288e73e974/build-end.log

Signed-off-by: Romain Naour <romain.naour@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/lensfun/lensfun.mk

@@ -34,6 +34,12 @@ else
 LENSFUN_CONF_OPTS += -DBUILD_LENSTOOL=OFF
 endif
 
+ifeq ($(BR2_STATIC_LIBS),y)
+LENSFUN_CONF_OPTS += -DBUILD_STATIC=ON
+else
+LENSFUN_CONF_OPTS += -DBUILD_STATIC=OFF
+endif
+
 # Don't install helper scripts (which require python3 and gksudo).
 # Don't run setup.py on the host.
 LENSFUN_CONF_OPTS += -DINSTALL_HELPER_SCRIPTS=OFF -DPYTHON=OFF