[PATCH] pif: Add message to static_assert for C11 compliance, fix build with gcc 8

[Stefano Brivio <sbrivio@redhat.com>]

Seen with gcc 8.5:

---
In file included from passt.h:18,
                 from qrap.c:36:
pif.h: In function 'pif_type':
pif.h:48:44: error: expected ',' before ')' token
  static_assert(sizeof("?") <= PIF_NAME_SIZE);
                                            ^
make: *** [Makefile:105: qrap] Error 1
---

As noted in ba84a3b17af8 ("treewide: Add messages to static_assert()
calls"), static_assert() calls need a message to comply with C11. The
form without message is supported starting from C23 only.

Fixes: cbcd4284111f ("pif: Limit pif names to 128 bytes")
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
---
 pif.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pif.h b/pif.h
index 3a1e2e5..dedcaa5 100644
--- a/pif.h
+++ b/pif.h
@@ -45,7 +45,7 @@ static inline const char *pif_type(enum pif_type pt)
 		return pif_type_str[pt];
 	else
 		return "?";
-	static_assert(sizeof("?") <= PIF_NAME_SIZE);
+	static_assert(sizeof("?") <= PIF_NAME_SIZE, "PIF_NAME_SIZE too small");
 }
 
 static inline const char *pif_name(uint8_t pif)
-- 
2.43.0