Do not write build info if there are no files to emit

src/compiler/builder.ts

@@ -251,6 +251,9 @@ namespace ts {
             state.seenAffectedFiles = createMap<true>();
         }
 
+        state.emittedBuildInfo = !state.changedFilesSet.size &&
+            !state.affectedFilesPendingEmit;
+
         return state;
     }
 

tests/baselines/reference/tsc/incremental/incremental-declaration-doesnt-change/when-passing-filename-for-buildinfo-on-commandline.js

@@ -3,4 +3,3 @@
 exitCode:: 0
 
 
-//// [/src/project/.tsbuildinfo] file written with same contents