util: Don't read over 'size - 1' bytes of source string in ovs_strlcpy().

The blind replacement of strncpy() by ovs_strlcpy() is risky because
strncpy() never reads more bytes from its source string than necessary to
write its destination string, but ovs_strlcpy() and the OpenBSD function
that inspired it both read the entire source string.  This avoids that
problem.

Given that change, we can use ovs_strlcpy() in a few more places, and
this commit does that too.

Coverity #10697,10696,10695,10694,10693,10692,10691,10690.

lib/util.c

@@ -137,14 +137,15 @@ xasprintf(const char *format, ...)
     return s;
 }
 
+/* Similar to strlcpy() from OpenBSD, but it never reads more than 'size - 1'
+ * bytes from 'src' and doesn't return anything. */
 void
 ovs_strlcpy(char *dst, const char *src, size_t size)
 {
     if (size > 0) {
-        size_t n = strlen(src);
-        size_t n_copy = MIN(n, size - 1);
-        memcpy(dst, src, n_copy);
-        dst[n_copy] = '\0';
+        size_t len = strnlen(src, size - 1);
+        memcpy(dst, src, len);
+        dst[len] = '\0';
     }
 }