[Callgraph] Remove "unsound" mention in help message

src/plugins/callgraph/options.ml

@@ -76,8 +76,7 @@ module Function_pointers =
       let option_name = "-cg-function-pointers"
       let help = "when Eva has not been computed, safely over-approximate \
                   callees in presence of function pointers; \
-                  always done when Eva has been previously computed. \
-                  WARNING: this option is unsound"
+                  always done when Eva has been previously computed."
     end)
 
 module Uncalled =