Rename fpos_t to avoid libc conflict

Marlin/SdBaseFile.cpp

   return true;
 }
 //------------------------------------------------------------------------------
-void SdBaseFile::getpos(fpos_t* pos) {
+void SdBaseFile::getpos(filepos_t* pos) {
   pos->position = curPosition_;
   pos->cluster = curCluster_;
 }
  * \return The byte if no error and not at eof else -1;
  */
 int SdBaseFile::peek() {
-  fpos_t pos;
+  filepos_t pos;
   getpos(&pos);
   int c = read();
   if (c >= 0) setpos(&pos);
   return false;
 }
 //------------------------------------------------------------------------------
-void SdBaseFile::setpos(fpos_t* pos) {
+void SdBaseFile::setpos(filepos_t* pos) {
   curPosition_ = pos->position;
   curCluster_ = pos->cluster;
 }

Marlin/SdBaseFile.h

 #include "SdVolume.h"
 //------------------------------------------------------------------------------
 /**
- * \struct fpos_t
+ * \struct filepos_t
  * \brief internal type for istream
  * do not use in user apps
  */
-struct fpos_t {
+struct filepos_t {
   /** stream position */
   uint32_t position;
   /** cluster for position */
   uint32_t cluster;
-  fpos_t() : position(0), cluster(0) {}
+  filepos_t() : position(0), cluster(0) {}
 };
 
 // use the gnu style oflag in open()
   /** get position for streams
    * \param[out] pos struct to receive position
    */
-  void getpos(fpos_t* pos);
+  void getpos(filepos_t* pos);
   /** set position for streams
    * \param[out] pos struct with value for new position
    */
-  void setpos(fpos_t* pos);
+  void setpos(filepos_t* pos);
   //----------------------------------------------------------------------------
   bool close();
   bool contiguousRange(uint32_t* bgnBlock, uint32_t* endBlock);