Allow user to override LWIP_PROVIDE_ERRNO

This doesn't allow LWIP_PROVIDE_ERRNO to be overridden:

Lines 40 to 42 in f0d19c3


	#define LWIP_PROVIDE_ERRNO

Suggest replacing with the following:

#if !defined(LWIP_ERRNO_STDINCLUDE) && !defined(LWIP_ERRNO_INCLUDE) && !defined(LWIP_PROVIDE_ERRNO)
#define LWIP_PROVIDE_ERRNO
#endif

to align with this comment:

stm32_mw_lwip/src/include/lwip/opt.h

Lines 47 to 52 in f0d19c3

    
           /* 
        
            * Include user defined options first. Anything not defined in these files 
        
            * will be set to standard values. Override anything you don't like! 
        
            */ 
        
           #include "lwipopts.h" 
        
           #include "lwip/debug.h"

I had a similar issue, although at least in my case I was able to override in lwipopts.h, with this: -

/* USER CODE BEGIN 1 /
#undef LWIP_PROVIDE_ERRNO
#define LWIP_ERRNO_STDINCLUDE
/ USER CODE END 1 */

It is obtuse and would be better implemented as suggested.

In my case, this comes about if you enable configUSE_NEWLIB_REENTRANT (also missing from CubeMX) for FreeRTOS (which is AFAIK required for proper threadsafe newlib usage).

ST Internal Reference: 126118

Isn't this the same problem as this? However that pull request just removes the errno declaration from Middlewares/Third_Party/LwIP/system/OS/sys_arch.c which does not seem to be correct.

	/*
	* Include user defined options first. Anything not defined in these files
	* will be set to standard values. Override anything you don't like!
	*/
	#include "lwipopts.h"
	#include "lwip/debug.h"