fix(pthread): Fix cxx pthread example build for linux platform

Closes https://github.com/espressif/esp-idf/pull/14339

components/pthread/CMakeLists.txt

@@ -1,7 +1,9 @@
 idf_build_get_property(target IDF_TARGET)
 if(${target} STREQUAL "linux")
-    # Make pthread component an empty interface lib referencing host pthread for Linux target
-    idf_component_register()
+    set(sources "port/linux/pthread.c")
+    idf_component_register(
+        SRCS ${sources}
+        INCLUDE_DIRS include)
     set(THREADS_PREFER_PTHREAD_FLAG ON)
     find_package(Threads REQUIRED)
     target_link_libraries(${COMPONENT_LIB} INTERFACE Threads::Threads)

components/pthread/port/linux/pthread.c

@@ -0,0 +1,43 @@
+/*
+ * SPDX-FileCopyrightText: 2024 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+/*
+ * pthread port for Linux build
+ */
+
+#include "esp_pthread.h"
+#include <string.h>
+
+/**
+ * @brief Creates a default pthread configuration based
+ * on the values set via menuconfig.
+ *
+ * @return
+ *      A default configuration structure.
+ */
+esp_pthread_cfg_t esp_pthread_get_default_config(void)
+{
+    esp_pthread_cfg_t cfg = {
+        .stack_size = CONFIG_PTHREAD_TASK_STACK_SIZE_DEFAULT,
+        .prio = CONFIG_PTHREAD_TASK_PRIO_DEFAULT,
+        .inherit_cfg = false,
+        .thread_name = NULL,
+        .pin_to_core = 0,
+        .stack_alloc_caps = 0,
+    };
+
+    return cfg;
+}
+
+esp_err_t esp_pthread_set_cfg(const esp_pthread_cfg_t *cfg)
+{
+    return ESP_OK;
+}
+
+esp_err_t esp_pthread_get_cfg(esp_pthread_cfg_t *p)
+{
+    memset(p, 0, sizeof(*p));
+    return ESP_ERR_NOT_FOUND;
+}

tools/test_apps/linux_compatible/generic_build_test/main/CMakeLists.txt

@@ -1,2 +1,3 @@
 idf_component_register(SRCS "generic_build_test.c"
-                    INCLUDE_DIRS ".")
+                    INCLUDE_DIRS "."
+                    PRIV_REQUIRES pthread)

tools/test_apps/linux_compatible/generic_build_test/main/generic_build_test.c

@@ -8,8 +8,13 @@
 #include <stddef.h>
 #include "inttypes_ext.h"
 
+#include "esp_pthread.h"
+
 void app_main(void)
 {
     size_t size = 47;
     printf("size is: %" PRIuSIZE "\n", size); // test IDF's PRIuSIZE
+
+    esp_pthread_cfg_t pthread_config = esp_pthread_get_default_config();
+    (void)pthread_config;
 }