BMessage::AddString() no longer crashes when the string to add is NULL.

git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@16410 a95241bf-73f2-0310-859d-f6bbb57e9c96

src/kits/app/Message.cpp

@@ -1287,7 +1287,7 @@ DEFINE_LAZY_FIND_FUNCTION(const char*	, String)
 status_t 
 BMessage::AddString(const char* name, const char* string)
 {
-	return AddData(name, B_STRING_TYPE, string, strlen(string) + 1);
+	return AddData(name, B_STRING_TYPE, string, string ? strlen(string) + 1 : 0);
 }
 
 

src/kits/app/Message4.cpp

@@ -2036,7 +2036,7 @@ DEFINE_LAZY_FIND_FUNCTION(double, Double, 0);
 status_t
 BMessage::AddString(const char *name, const char *string)
 {
-	return AddData(name, B_STRING_TYPE, string, strlen(string) + 1, false);
+	return AddData(name, B_STRING_TYPE, string, string ? strlen(string) + 1 : 0, false);
 }