fix(examples): idf_as_lib linux build

The Linux build was broken after IDF flash API was updated without updating
the Linux stub library in the example. This commit updates the spi_flash stub
library such that:

- The API now matches same API as IDF's spi_flash component
- Links the stub_esp32 library to pull in basic types and defines

Author: Dazza0

examples/build_system/cmake/idf_as_lib/stubs/esp32/CMakeLists.txt

@@ -1,5 +1,3 @@
 add_library(stub_esp32 STATIC system_api.c cpu_start.c)
 target_include_directories(stub_esp32 PUBLIC .)
 add_library(stub::esp32 ALIAS stub_esp32)
-
-target_link_libraries(stub_esp32 stub::spi_flash)

examples/build_system/cmake/idf_as_lib/stubs/esp32/esp_system.h

@@ -9,6 +9,10 @@
 extern "C" {
 #endif
 
+#define ESP_OK          0       /*!< esp_err_t value indicating success (no error) */
+
+typedef int esp_err_t;
+
 void esp_restart(void);
 
 #ifdef __cplusplus

examples/build_system/cmake/idf_as_lib/stubs/spi_flash/CMakeLists.txt

@@ -1,3 +1,4 @@
 add_library(stub_spi_flash STATIC flash_ops.c)
-target_include_directories(stub_spi_flash INTERFACE .)
+target_include_directories(stub_spi_flash PUBLIC .)
 add_library(stub::spi_flash ALIAS stub_spi_flash)
+target_link_libraries(stub_spi_flash PUBLIC stub_esp32)

examples/build_system/cmake/idf_as_lib/stubs/spi_flash/esp_flash.h

@@ -1,18 +1,21 @@
 /*
- * SPDX-FileCopyrightText: 2022 Espressif Systems (Shanghai) CO LTD
+ * SPDX-FileCopyrightText: 2022-2025 Espressif Systems (Shanghai) CO LTD
  *
  * SPDX-License-Identifier: Unlicense OR CC0-1.0
  */
 
 #pragma once
 
-#include <stddef.h>
+#include <stdint.h>
+#include "esp_system.h"
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-int spi_flash_get_chip_size(void);
+typedef void * esp_flash_t;
+
+esp_err_t esp_flash_get_size(esp_flash_t *chip, uint32_t *out_size);
 
 #ifdef __cplusplus
 }

examples/build_system/cmake/idf_as_lib/stubs/spi_flash/flash_ops.c

@@ -1,10 +1,13 @@
 /*
- * SPDX-FileCopyrightText: 2022 Espressif Systems (Shanghai) CO LTD
+ * SPDX-FileCopyrightText: 2022-2025 Espressif Systems (Shanghai) CO LTD
  *
  * SPDX-License-Identifier: Unlicense OR CC0-1.0
  */
 
-int spi_flash_get_chip_size(void)
+#include "esp_flash.h"
+
+esp_err_t esp_flash_get_size(esp_flash_t *chip, uint32_t *out_size)
 {
-    return (1024 * 1024 * 1024);
+    *out_size = 1024 * 1024 * 1024;
+    return ESP_OK;
 }