Feature/add memap cstack usage ports (#661)

* Added memap, avstack, and checkstackusage tools to STM32F4xx Makefile and CMake builds to calculate CSTACK depth and RAM usage

* Added memap, cstack, and ram-usage recipes to stm32f10x port Makefile.  Added Cmake build.

* Removed local dlmstp.c module from stm32f10x port, and used the common datalink dlmstp.c module with MS/TP extended frames and zero-config support.

* Added .nm and .su to .gitignore to skip the analysis file residue.

ports/stm32f10x/drivers/src/syscalls.c

@@ -20,8 +20,6 @@
 extern int errno;
 extern int __io_putchar(int ch);
 
-register char * stack_ptr asm("sp");
-
 char *__env[1] = { 0 };
 char **environ = __env;
 
@@ -61,6 +59,7 @@ int _write(int file, char *ptr, int len)
 
 caddr_t _sbrk(int incr)
 {
+	register char * stack_ptr asm("sp");
 	extern char end asm("end");
 	static char *heap_end;
 	char *prev_heap_end;