changed returned text in noOutput to same but allocated text

it could possibly cause deallocattion problems

src/lib/flags.c

@@ -1,5 +1,7 @@
 #include <why2/flags.h>
 
+#include <stdlib.h>
+
 unsigned long getKeyLength()
 {
     return keyLength;
@@ -12,7 +14,12 @@ inputFlags noFlags()
 
 outputFlags noOutput(unsigned char exitCode)
 {
-    return (outputFlags) {"", "", 0, 0, exitCode};
+    char *empty1 = malloc(1);
+    char *empty2 = malloc(1);
+    empty1[0] = '\0';
+    empty2[0] = '\0';
+
+    return (outputFlags) { empty1, empty2, 0, 0, exitCode };
 }
 
 void setKeyLength(int keyLengthNew)