Core: Modernize C headers with C++ equivalents

drivers/unix/os_unix.cpp

@@ -69,19 +69,18 @@
 #endif
 
 #include <dlfcn.h>
-#include <errno.h>
 #include <poll.h>
-#include <signal.h>
-#include <stdarg.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
 #include <sys/resource.h>
 #include <sys/stat.h>
 #include <sys/time.h>
 #include <sys/wait.h>
-#include <time.h>
 #include <unistd.h>
+#include <cerrno>
+#include <csignal>
+#include <cstdarg>
+#include <cstdio>
+#include <cstdlib>
+#include <ctime>
 
 #ifndef RTLD_DEEPBIND
 #define RTLD_DEEPBIND 0