Update fuzzer sources

tests/fuzz/fuzz.h

@@ -12,15 +12,17 @@
  * Fuzz targets have some common parameters passed as macros during compilation.
  * Check the documentation for each individual fuzzer for more parameters.
  *
- * @param STATEFULL_FUZZING:
+ * @param STATEFUL_FUZZING:
  *        Define this to reuse state between fuzzer runs. This can be useful to
  *        test code paths which are only executed when contexts are reused.
  *        WARNING: Makes reproducing crashes much harder.
  *        Default: Not defined.
  * @param FUZZ_RNG_SEED_SIZE:
  *        The number of bytes of the source to look at when constructing a seed
- *        for the deterministic RNG.
- *        Default: 128.
+ *        for the deterministic RNG. These bytes are discarded before passing
+ *        the data to zstd functions. Every fuzzer initializes the RNG exactly
+ *        once before doing anything else, even if it is unused.
+ *        Default: 4.
  * @param ZSTD_DEBUG:
  *        This is a parameter for the zstd library. Defining `ZSTD_DEBUG=1`
  *        enables assert() statements in the zstd library. Higher levels enable
@@ -41,12 +43,20 @@
 #define FUZZ_H
 
 #ifndef FUZZ_RNG_SEED_SIZE
-#  define FUZZ_RNG_SEED_SIZE 128
+#  define FUZZ_RNG_SEED_SIZE 4
 #endif
 
 #include <stddef.h>
 #include <stdint.h>
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 int LLVMFuzzerTestOneInput(const uint8_t *src, size_t size);
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif