Fix linking issue with irrXML

contrib/irrXML/CMakeLists.txt

@@ -11,3 +11,7 @@ set( IrrXML_SRCS
 add_library(IrrXML STATIC ${IrrXML_SRCS})
 set(IRRXML_INCLUDE_DIR "${CMAKE_CURRENT_SOURCE_DIR}" CACHE INTERNAL "IrrXML_Include" )
 set(IRRXML_LIBRARY "IrrXML" CACHE INTERNAL "IrrXML" )
+
+install(TARGETS IrrXML
+  ARCHIVE DESTINATION ${ASSIMP_LIB_INSTALL_DIR}
+  COMPONENT ${LIBASSIMP_COMPONENT})