Fix -Wundef warnings in coroutine/*/Context.h

* See [Feature #17752]

Co-authored-by: xtkoba (Tee KOBAYASHI) <xtkoba+ruby@gmail.com>

coroutine/copy/Context.h

@@ -23,9 +23,12 @@
 
 #define COROUTINE __attribute__((noreturn)) void
 
+#ifdef HAVE_STDINT_H
+#include <stdint.h>
 #if INTPTR_MAX <= INT32_MAX
 #define COROUTINE_LIMITED_ADDRESS_SPACE
 #endif
+#endif
 
 // This stack copying implementation which uses a private stack for each coroutine, including the main one.
 #define COROUTINE_PRIVATE_STACK

coroutine/ucontext/Context.h

@@ -16,9 +16,12 @@
 
 #define COROUTINE __attribute__((noreturn)) void
 
+#ifdef HAVE_STDINT_H
+#include <stdint.h>
 #if INTPTR_MAX <= INT32_MAX
 #define COROUTINE_LIMITED_ADDRESS_SPACE
 #endif
+#endif
 
 struct coroutine_context
 {