added prototype for basic oops handler function

include/nickel/oops.h

@@ -0,0 +1,31 @@
+#ifndef __NICKEL_OOPS_H
+#define __NICKEL_OOPS_H
+
+#include <sys/types.h>
+#include <stdlib.h>
+
+#include <unistd.h>
+#include <errno.h>
+#include <string.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+// TODO: C23 adds [[noreturn]] (& [[]] function attribute tags)
+// which are standardized, the below depends on compiler support.
+#if defined(__GNUC__) || defined(__CLANG__)
+#define NORETURN __attribute__ ((__noreturn__))
+#else
+#define NORETURN
+#endif /* __GNUC__ || __CLANG__*/
+
+void nickel_oops_handler(const char *format, ...) NORETURN;
+
+#ifdef __cplusplus
+}
+#endif
+
+// clean up our noreturn define
+#undef NORETURN
+#endif