windows: Sync mpconfigport.h with the unix' version

- rearrange/add definitions that were not there so it's easier to compare both
- use MICROPY_PY_SYS_PLATFORM in main.c since it's available anyway
- define EWOULDBLOCK, it is missing from ingw32

unix/main.c

@@ -147,7 +147,7 @@ STATIC char *strjoin(const char *s1, int sep_char, const char *s2) {
 }
 
 STATIC void do_repl(void) {
-    printf("Micro Python " MICROPY_GIT_TAG " on " MICROPY_BUILD_DATE "; UNIX version\n");
+    printf("Micro Python " MICROPY_GIT_TAG " on " MICROPY_BUILD_DATE "; " MICROPY_PY_SYS_PLATFORM " version\n");
 
     for (;;) {
         char *line = prompt(">>> ");