Fix compilation for use as IDF component (#5265)

libraries/LITTLEFS/src/LITTLEFS.cpp

@@ -20,11 +20,15 @@ extern "C" {
 #include <sys/unistd.h>
 #include <sys/stat.h>
 #include <dirent.h>
-#include "esp_littlefs.h"
 }
-
+#include "sdkconfig.h"
 #include "LITTLEFS.h"
 
+#ifdef CONFIG_LITTLEFS_PAGE_SIZE
+extern "C" {
+    #include "esp_littlefs.h"
+}
+
 using namespace fs;
 
 class LITTLEFSImpl : public VFSImpl
@@ -137,4 +141,4 @@ size_t LITTLEFSFS::usedBytes()
 }
 
 LITTLEFSFS LITTLEFS;
-
+#endif