std-aux: add NM_IFNAMSIZE

src/libnm-std-aux/nm-std-aux.h

@@ -1367,6 +1367,12 @@ nm_ptr_to_uintptr(const void *p)
 
 /*****************************************************************************/
 
+/* IFNAMSIZ is both defined in <linux/if.h> and <net/if.h>. In the past, these
+ * headers conflicted, so we cannot simply include either of them in a header-file.*/
+#define NM_IFNAMSIZ 16
+
+/*****************************************************************************/
+
 #define NM_AF_UNSPEC 0  /* AF_UNSPEC */
 #define NM_AF_INET   2  /* AF_INET   */
 #define NM_AF_INET6  10 /* AF_INET6  */

src/libnm-std-aux/nm-std-utils.c

@@ -7,9 +7,13 @@
 #include <stdint.h>
 #include <assert.h>
 #include <limits.h>
+#include <net/if.h>
 
 /*****************************************************************************/
 
+NM_STATIC_ASSERT(NM_IFNAMSIZ == IFNAMSIZ);
+
+/*****************************************************************************/
 size_t
 nm_utils_get_next_realloc_size(bool true_realloc, size_t requested)
 {