unix/mphalport.h: Fix build when MICROPY_USE_READLINE=0.

If the built-in input() is enabled (which it is by default) then it needs
some form of readline, so supply it with one when MICROPY_USE_READLINE=0.

Fixes issue micropython#5658.

Author: dpgeorge

ports/unix/mphalport.h

@@ -35,7 +35,21 @@ void mp_hal_set_interrupt_char(char c);
 void mp_hal_stdio_mode_raw(void);
 void mp_hal_stdio_mode_orig(void);
 
-#if MICROPY_USE_READLINE == 1 && MICROPY_PY_BUILTINS_INPUT
+#if MICROPY_PY_BUILTINS_INPUT && MICROPY_USE_READLINE == 0
+
+#include <malloc.h>
+#include "py/misc.h"
+#include "input.h"
+#define mp_hal_readline mp_hal_readline
+static inline int mp_hal_readline(vstr_t *vstr, const char *p) {
+    char *line = prompt((char*)p);
+    vstr_add_str(vstr, line);
+    free(line);
+    return 0;
+}
+
+#elif MICROPY_PY_BUILTINS_INPUT && MICROPY_USE_READLINE == 1
+
 #include "py/misc.h"
 #include "lib/mp-readline/readline.h"
 // For built-in input() we need to wrap the standard readline() to enable raw mode
@@ -46,6 +60,7 @@ static inline int mp_hal_readline(vstr_t *vstr, const char *p) {
     mp_hal_stdio_mode_orig();
     return ret;
 }
+
 #endif
 
 // TODO: POSIX et al. define usleep() as guaranteedly capable only of 1s sleep: