package/yaml-cpp: build shared library if needed

yaml-cpp builds only a static library by default, this will raise a
build failure with upcoming mongodb 4.2.x as reported by Ryan Barnett
due to mongodb linking with a static library that obviously will miss
-fPIC

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/yaml-cpp/yaml-cpp.mk

@@ -15,4 +15,10 @@ YAML_CPP_CONF_OPTS += \
 	-DYAML_CPP_BUILD_TESTS=OFF \
 	-DYAML_CPP_BUILD_TOOLS=OFF
 
+ifeq ($(BR2_STATIC_LIBS),y)
+YAML_CPP_CONF_OPTS += -DYAML_BUILD_SHARED_LIBS=OFF
+else
+YAML_CPP_CONF_OPTS += -DYAML_BUILD_SHARED_LIBS=ON
+endif
+
 $(eval $(cmake-package))