Use _ instead of exists variable x2

Author: owen-mc

go/ql/lib/semmle/go/dataflow/SsaImpl.qll

@@ -349,10 +349,8 @@ private module Internal {
       varBlockReachesBaseCand(v, b1, b2) and
       blockPrecedesVar(v, b2)
       or
-      exists(ReachableBasicBlock mid |
-        varBlockReachesRecCand(v, b1, mid, b2) and
-        blockPrecedesVar(v, b2)
-      )
+      varBlockReachesRecCand(v, b1, _, b2) and
+      blockPrecedesVar(v, b2)
     }
 
     /**

go/ql/lib/semmle/go/security/LogInjectionCustomizations.qll

@@ -79,9 +79,7 @@ module LogInjection {
    */
   private class SafeFormatArgumentSanitizer extends Sanitizer {
     SafeFormatArgumentSanitizer() {
-      exists(DataFlow::Node arg, StringOps::Formatting::StringFormatCall call |
-        safeFormatArgument(arg, call)
-      |
+      exists(StringOps::Formatting::StringFormatCall call | safeFormatArgument(_, call) |
         this = call.getAResult()
       )
     }