Switch from C headers to C++ headers.

This CL makes the following substitutions.

* assert.h -> cassert
* math.h -> cmath
* stdarg.h -> cstdarg
* stdio.h -> cstdio
* stdlib.h -> cstdlib
* string.h -> cstring

stddef.h and stdint.h are not migrated to C++ headers.

PiperOrigin-RevId: 309074805

snappy_compress_fuzzer.cc

@@ -28,9 +28,10 @@
 //
 // libFuzzer harness for fuzzing snappy compression code.
 
+#include <stddef.h>
+#include <stdint.h>
+
 #include <cassert>
-#include <cstddef>
-#include <cstdint>
 #include <string>
 
 #include "snappy.h"