[PATCH] util: Add own prototype for __clone2() on ia64

[Stefano Brivio <sbrivio@redhat.com>]

ia64 needs to use __clone2() as clone() is not available, but glibc
doesn't export the prototype. Take it from clone(2) to avoid an
implicit declaration:

util.c: In function ‘do_clone’:
util.c:512:16: warning: implicit declaration of function ‘__clone2’ [-Wimplicit-function-declaration]
  512 |         return __clone2(fn, stack_area + stack_size / 2, stack_size / 2,
      |                ^~~~~~~~

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
---
 util.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/util.c b/util.c
index c5ee1c0..799173f 100644
--- a/util.c
+++ b/util.c
@@ -495,6 +495,15 @@ int write_file(const char *path, const char *buf)
 	return len == 0 ? 0 : -1;
 }
 
+#ifdef __ia64__
+/* Needed by do_clone() below: glibc doesn't export the prototype of __clone2(),
+ * use the description from clone(2).
+ */
+int __clone2(int (*fn)(void *), void *stack_base, size_t stack_size, int flags,
+	     void *arg, ... /* pid_t *parent_tid, struct user_desc *tls,
+	     pid_t *child_tid */ );
+#endif
+
 /**
  * do_clone() - Wrapper of __clone2() for ia64, clone() for other architectures
  * @fn:		Entry point for child
-- 
@@ -495,6 +495,15 @@ int write_file(const char *path, const char *buf)
 	return len == 0 ? 0 : -1;
 }
 
+#ifdef __ia64__
+/* Needed by do_clone() below: glibc doesn't export the prototype of __clone2(),
+ * use the description from clone(2).
+ */
+int __clone2(int (*fn)(void *), void *stack_base, size_t stack_size, int flags,
+	     void *arg, ... /* pid_t *parent_tid, struct user_desc *tls,
+	     pid_t *child_tid */ );
+#endif
+
 /**
  * do_clone() - Wrapper of __clone2() for ia64, clone() for other architectures
  * @fn:		Entry point for child
-- 
2.39.1