Update git submodule again and disable Write-strings warning

.gitmodules

@@ -4,4 +4,4 @@
 
 [submodule "lib/ipfs-http-client"]
 	path = lib/ipfs-http-client
-	url = https://github.com/danger89/cpp-ipfs-http-client.git
+	url = https://github.com/vasild/cpp-ipfs-http-client.git

src/ipfs.cc

@@ -15,8 +15,13 @@ int IPFS::startIPFSDaemon()
     dup2(fd, 2); // ..and same with stderr
     close(fd);   // close fd
 
+    // Ignore ISO C++ forbids converting a string constant to ‘char*’
+    // This is valid in C.
+    #pragma GCC diagnostic push
+    #pragma GCC diagnostic ignored "-Wwrite-strings"
     // stdout and stderr now write to /dev/null
     // Ready to call exec to start IPFS Daemon
-    constexpr char *proc[] = { "../../go-ipfs/ipfs", "daemon", "--init", "--migrate", 0};
+    constexpr char *proc[] = { "../../go-ipfs/ipfs", "daemon", "--init", "--migrate", NULL};
+    #pragma GCC diagnostic pop
     return execv(proc[0], proc);
 }