Changing the update of the option variables for generate_avr_library

The option lists for HDRS and LIBS in generate_avr_library are
producing mixed up lists if the set function is used with
a space character as delimiter between option name and rest of
list. Using list function for inserting option name helped.

Author: TheMiles

cmake/Platform/Arduino.cmake

@@ -429,6 +429,14 @@ function(GENERATE_AVR_LIBRARY INPUT_NAME)
         set( INPUT_LIBS "LIBS ${INPUT_LIBS}" )
     endif()
 
+    if(INPUT_HDRS)
+        list(INSERT INPUT_HDRS 0 "HDRS")
+    endif()
+    if(INPUT_LIBS)
+        list(INSERT INPUT_LIBS 0 "LIBS")
+    endif()
+
+
     generate_arduino_library( ${INPUT_NAME} 
         NO_AUTOLIBS
         MANUAL