BUILD: server: check->desc always exists

Clang reports this warning :

  src/server.c:872:14: warning: address of array 'check->desc' will
  always evaluate to 'true' [-Wpointer-bool-conversion]

Indeed, check->desc used to be a pointer to a dynamically allocated area
a long time ago and is now an array. Let's remove the useless test.
diff --git a/src/server.c b/src/server.c
index 5e995f8..c712b88 100644
--- a/src/server.c
+++ b/src/server.c
@@ -869,8 +869,7 @@
 		strlcpy2(s->op_st_chg.reason, reason, sizeof(s->op_st_chg.reason));
 	}
 	else if (check) {
-		if (check->desc)
-			strlcpy2(s->op_st_chg.reason, check->desc, sizeof(s->op_st_chg.reason));
+		strlcpy2(s->op_st_chg.reason, check->desc, sizeof(s->op_st_chg.reason));
 		s->op_st_chg.code = check->code;
 		s->op_st_chg.status = check->status;
 		s->op_st_chg.duration = check->duration;
@@ -908,8 +907,7 @@
 		strlcpy2(s->op_st_chg.reason, reason, sizeof(s->op_st_chg.reason));
 	}
 	else if (check) {
-		if (check->desc)
-			strlcpy2(s->op_st_chg.reason, check->desc, sizeof(s->op_st_chg.reason));
+		strlcpy2(s->op_st_chg.reason, check->desc, sizeof(s->op_st_chg.reason));
 		s->op_st_chg.code = check->code;
 		s->op_st_chg.status = check->status;
 		s->op_st_chg.duration = check->duration;
@@ -952,8 +950,7 @@
 		strlcpy2(s->op_st_chg.reason, reason, sizeof(s->op_st_chg.reason));
 	}
 	else if (check) {
-		if (check->desc)
-			strlcpy2(s->op_st_chg.reason, check->desc, sizeof(s->op_st_chg.reason));
+		strlcpy2(s->op_st_chg.reason, check->desc, sizeof(s->op_st_chg.reason));
 		s->op_st_chg.code = check->code;
 		s->op_st_chg.status = check->status;
 		s->op_st_chg.duration = check->duration;