Fix FTBFS with OpenJDK 11 by build-depending on libactivation-java.

Closes: #912541

debian/control

@@ -10,6 +10,7 @@ Build-Depends:
  default-jdk,
  default-jdk-doc,
  javahelper (>= 0.30),
+ libactivation-java,
  libasm-java (>= 5.0),
  libjarjar-java,
  libjoda-time-java,

debian/rules

@@ -8,7 +8,7 @@ override_dh_auto_build: mklibdirs
 	ln -s /usr/share/java/jsr311-api.jar lib/jaxrs/jsr311-api.jar || true
 	ln -s /usr/share/java/asm.jar lib/ext/asm/asm-3.3.jar || true
 	ln -s /usr/share/java/jarjar.jar lib/ext/jarjar/jarjar-1.0.jar || true
-	CLASSPATH="/usr/share/java/net.luminis.build.plugin.jar:/usr/share/java/bnd.jar" \
+	CLASSPATH="/usr/share/java/net.luminis.build.plugin.jar:/usr/share/java/bnd.jar:/usr/share/java/javax.activation.jar" \
 		ant -buildfile debian/build.xml repackage-asm compile.main jars javadoc \
 			generate-poms