fix(esp_tee): build esp_tee only with CONFIG_LIBC_NEWLIB to reduce size

components/newlib/src/picolibc/picolibc_init.c

@@ -37,8 +37,55 @@ int __retarget_lock_try_acquire(struct __lock * p);
 int __retarget_lock_try_acquire_recursive(struct __lock *p);
 #endif
 
+#if CONFIG_SECURE_ENABLE_TEE
+struct _reent_stub {
+    int _errno;
+    __FILE *_stdin, *_stdout, *_stderr;
+    int _inc;
+    char *_emergency;
+    int _reserved_0;
+    int _reserved_1;
+    struct __locale_t *_locale;
+    void *_mp;
+    void (*__cleanup)(struct _reent *);
+    int _gamma_signgam;
+    int _cvtlen;
+    char *_cvtbuf;
+    struct _rand48 *_r48;
+#if 0 /* unlikely used fields in ROM implementation */
+    struct __tm *_localtime_buf;
+    char *_asctime_buf;
+    void (** _sig_func)(int);
+    struct _atexit *_reserved_6;
+    struct _atexit _reserved_7;
+    struct _glue _reserved_8;
+    __FILE *__sf;
+    struct _misc_reent *_misc;
+    char *_signal_buf;
+#endif
+};
+
+void *__getreent_rom_stub(void)
+{
+    static struct _reent_stub reent_stub;
+    return &reent_stub;
+}
+#endif // SECURE_ENABLE_TEE
+
 static struct syscall_stub_table s_stub_table = {
+#if CONFIG_SECURE_ENABLE_TEE
+    /*
+     * ESP-TEE uses snprintf() from ROM, which requires at least a fake __getreent stub.
+     *
+     * NOTE: If floating-point variables are intended to be used,
+     *       the following fields must be specified in the syscall_stub_table:
+     *   ._printf_float =
+     *   ._scanf_float =
+     */
+    .__getreent = (void *)__getreent_rom_stub,
+#else
     .__getreent = (void *)abort,
+#endif
     ._malloc_r = (void *)abort,
     ._free_r = (void *)abort,
     ._realloc_r = (void *)abort,