py: Fix up so that it can compile without float.

py/gc.c

 #include <stdio.h>
-#include <stdlib.h>
 #include <string.h>
 
 #include "mpconfig.h"

py/malloc.c

-#include <unistd.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>

py/objstr.c

@@ -788,9 +788,9 @@ mp_obj_t str_format(uint n_args, const mp_obj_t *args) {
                     nlr_jump(mp_obj_new_exception_msg_varg(&mp_type_ValueError,
                         "Unknown format code '%c' for object of type '%s'", type, mp_obj_get_type_str(arg)));
             }
-        }
+
 #if MICROPY_ENABLE_FLOAT
-        if (arg_looks_numeric(arg)) {
+        } else if (arg_looks_numeric(arg)) {
             if (!type) {
 
                 // Even though the docs say that an unspecified type is the same
@@ -848,10 +848,14 @@ mp_obj_t str_format(uint n_args, const mp_obj_t *args) {
                         type, mp_obj_get_type_str(arg)));
             }
 #endif
+
         } else {
+            // arg doesn't look like a number
+
             if (align == '=') {
                 nlr_jump(mp_obj_new_exception_msg(&mp_type_ValueError, "'=' alignment not allowed in string format specifier"));
             }
+
             switch (type) {
                 case '\0':
                     mp_obj_print_helper((void (*)(void*, const char*, ...))vstr_printf, vstr, arg, PRINT_STR);

py/runtime.c

@@ -346,8 +346,7 @@ mp_obj_t mp_binary_op(int op, mp_obj_t lhs, mp_obj_t rhs) {
                 case MP_BINARY_OP_TRUE_DIVIDE:
                 case MP_BINARY_OP_INPLACE_TRUE_DIVIDE:
                     if (rhs_val == 0) {
-zero_division:
-                        nlr_jump(mp_obj_new_exception_msg(&mp_type_ZeroDivisionError, "division by zero"));
+                        goto zero_division;
                     }
                     return mp_obj_new_float((mp_float_t)lhs_val / (mp_float_t)rhs_val);
                 #endif
@@ -451,6 +450,9 @@ generic_binary_op:
         "unsupported operand types for binary operator: '%s', '%s'",
         mp_obj_get_type_str(lhs), mp_obj_get_type_str(rhs)));
     return mp_const_none;
+
+zero_division:
+    nlr_jump(mp_obj_new_exception_msg(&mp_type_ZeroDivisionError, "division by zero"));
 }
 
 mp_obj_t mp_call_function_0(mp_obj_t fun) {