cmake: use VPP package in VOM

Change-Id: I83b244be920521e580085beffb7e40613e67c8ee
Signed-off-by: Damjan Marion <damarion@cisco.com>
diff --git a/src/cmake/library.cmake b/src/cmake/library.cmake
index e0eb7af..b9e4f9b 100644
--- a/src/cmake/library.cmake
+++ b/src/cmake/library.cmake
@@ -21,7 +21,9 @@
 
   add_library(${lib} SHARED ${ARG_SOURCES})
   target_compile_options(${lib} PRIVATE -Wall)
-  set_target_properties(${lib} PROPERTIES SOVERSION ${VPP_LIB_VERSION})
+  if(VPP_LIB_VERSION)
+    set_target_properties(${lib} PROPERTIES SOVERSION ${VPP_LIB_VERSION})
+  endif()
 
   # library deps
   if(ARG_LINK_LIBRARIES)