Bug 1365994 - Update libfuzzer r=decoder

MozReview-Commit-ID: GCwIIZd5PTS
***
1365994 - update moz.build for libfuzzer

MozReview-Commit-ID: IxbLnviJC08

tools/fuzzing/libfuzzer/FuzzerExtFunctionsWeak.cpp

@@ -16,6 +16,7 @@
 #if LIBFUZZER_LINUX
 
 #include "FuzzerExtFunctions.h"
+#include "FuzzerIO.h"
 
 extern "C" {
 // Declare these symbols as weak to allow them to be optionally defined.
@@ -46,5 +47,7 @@ ExternalFunctions::ExternalFunctions() {
 
 #undef EXT_FUNC
 }
+
 } // namespace fuzzer
+
 #endif // LIBFUZZER_LINUX