cmake: fix clang build and few minor fixes

Change-Id: If5b850c939f7a5383f9a7eff8ac41708c3428a90
Signed-off-by: Damjan Marion <damarion@cisco.com>
diff --git a/src/vpp-api/vapi/CMakeLists.txt b/src/vpp-api/vapi/CMakeLists.txt
index 8feb12e..103e7c5 100644
--- a/src/vpp-api/vapi/CMakeLists.txt
+++ b/src/vpp-api/vapi/CMakeLists.txt
@@ -50,7 +50,7 @@
   list(APPEND VAPICLIENT_API_CPP_HEADERS ${output})
 endforeach ()
 
-add_custom_target(all-vapi-headers ALL DEPENDS
+add_custom_target(all-vapi-headers DEPENDS
   ${VAPICLIENT_API_C_HEADERS}
   ${VAPICLIENT_API_CPP_HEADERS}
 )
@@ -61,6 +61,7 @@
   libvapiclient.map
 
   LINK_LIBRARIES vppinfra vlibmemoryclient svm pthread m rt
+  DEPENDS all-vapi-headers
 )
 
 install(