Compilation issues with Nextion and "utoa" fuction


So i have been using my Mega and Nextion successfully and now i have decided to try the Intel Edison.
As i have found out the Edison does not like the Nextion library especially the function "utoa" which is used throughout the Nextion library.

After much searching I found a this thread which says to past the following into the header file (Nextion.h)

extern "C" char* utoa(int a, char* buffer, unsigned char radix);

I have added it in and successfully reduced the issue but now i get this error during compilation

libraries\ITEADLIB_Arduino_Nextion-master\NexCrop.cpp.o: In function NexCrop::setPic(unsigned int)':* *\\Mac\Home\Documents\Arduino\libraries\ITEADLIB_Arduino_Nextion-master/NexCrop.cpp:61: undefined reference to utoa'
collect2.exe: error: ld returned 1 exit status

What am i missing here to resolve this issue?