Commit 44ce1b5d2fc ("migration/rdma: define htonll/ntohll
only if not predefined") tried to only include htonll/ntohll
replacements when their symbol is *defined*, but this doesn't
work, as they aren't:

  ../migration/rdma.c:242:17: error: static declaration of 'htonll' follows non-static declaration
    242 | static uint64_t htonll(uint64_t v)
        |                 ^~~~~~
  In file included from /usr/include/netinet/in.h:73,
                   from /usr/include/sys/socket.h:32,
                   from /home/f4bug/qemu/include/system/os-posix.h:30,
                   from /home/f4bug/qemu/include/qemu/osdep.h:176,
                   from ../migration/rdma.c:17:
  /usr/include/sys/byteorder.h:75:18: note: previous declaration of 'htonll' with type 'uint64_t(uint64_t)' {aka 'long unsigned int(long unsigned int)'}
     75 | extern  uint64_t htonll(uint64_t);
        |                  ^~~~~~
  ../migration/rdma.c:252:17: error: static declaration of 'ntohll' follows non-static declaration
    252 | static uint64_t ntohll(uint64_t v)
        |                 ^~~~~~
  /usr/include/sys/byteorder.h:76:18: note: previous declaration of 'ntohll' with type 'uint64_t(uint64_t)' {aka 'long unsigned int(long unsigned int)'}
     76 | extern  uint64_t ntohll(uint64_t);
        |                  ^~~~~~

Better to check the symbol availability with meson.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Acked-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20251117203834.83713-3-philmd@linaro.org>
---
 meson.build      | 1 +
 migration/rdma.c | 4 +---
 2 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/meson.build b/meson.build
index 5ddec8afd7b..81f9f7b3287 100644
--- a/meson.build
+++ b/meson.build
@@ -2663,6 +2663,7 @@ config_host_data.set('CONFIG_SYNCFS', cc.has_function('syncfs'))
 config_host_data.set('CONFIG_SYNC_FILE_RANGE', cc.has_function('sync_file_range'))
 config_host_data.set('CONFIG_TIMERFD', cc.has_function('timerfd_create'))
 config_host_data.set('CONFIG_GETLOADAVG', cc.has_function('getloadavg'))
+config_host_data.set('CONFIG_ARPA_INET_64', cc.has_function('htonll'))
 config_host_data.set('HAVE_COPY_FILE_RANGE', cc.has_function('copy_file_range'))
 config_host_data.set('HAVE_GETIFADDRS', cc.has_function('getifaddrs'))
 config_host_data.set('HAVE_GLIB_WITH_SLICE_ALLOCATOR', glib_has_gslice)
diff --git a/migration/rdma.c b/migration/rdma.c
index 2d839fce6c4..337b4158899 100644
--- a/migration/rdma.c
+++ b/migration/rdma.c
@@ -238,7 +238,7 @@ static const char *control_desc(unsigned int rdma_control)
     return strs[rdma_control];
 }
 
-#if !defined(htonll)
+#if !defined(CONFIG_ARPA_INET_64)
 static uint64_t htonll(uint64_t v)
 {
     union { uint32_t lv[2]; uint64_t llv; } u;
@@ -246,9 +246,7 @@ static uint64_t htonll(uint64_t v)
     u.lv[1] = htonl(v & 0xFFFFFFFFULL);
     return u.llv;
 }
-#endif
 
-#if !defined(ntohll)
 static uint64_t ntohll(uint64_t v)
 {
     union { uint32_t lv[2]; uint64_t llv; } u;
-- 
2.51.0