Add ifndef brackets around configuration settings

To allow users to override the library settings at compile time with
platform.txt options, bracked the configuration #defines with #ifndef.

Author: earlephilhower

src/SdFatConfig.h

@@ -38,7 +38,9 @@
  * Set INCLUDE_SDIOS nonzero to include sdios.h in SdFat.h.
  * sdios.h provides C++ style IO Streams.
  */
-#define INCLUDE_SDIOS 1
+#ifndef INCLUDE_SDIOS
+  #define INCLUDE_SDIOS 0
+#endif
 
 //------------------------------------------------------------------------------
 /**
@@ -59,7 +61,9 @@
  *  * (asterisk)
  *
  */
-#define USE_LONG_FILE_NAMES 1
+#ifndef USE_LONG_FILE_NAMES
+  #define USE_LONG_FILE_NAMES 1
+#endif
 //------------------------------------------------------------------------------
 /**
  * If the symbol ENABLE_EXTENDED_TRANSFER_CLASS is nonzero, the class SdFatEX
@@ -69,7 +73,9 @@
  * These classes used extended multi-block SD I/O for better performance.
  * the SPI bus may not be shared with other devices in this mode.
  */
-#define ENABLE_EXTENDED_TRANSFER_CLASS 0
+#ifndef ENABLE_EXTENDED_TRANSFER_CLASS
+  #define ENABLE_EXTENDED_TRANSFER_CLASS 0
+#endif
 //------------------------------------------------------------------------------
 /**
  * If the symbol USE_STANDARD_SPI_LIBRARY is zero, an optimized custom SPI
@@ -78,14 +84,18 @@
  * USE_STANDARD_SPI_LIBRARY is two, the SPI port can be selected with the
  * constructors SdFat(SPIClass* spiPort) and SdFatEX(SPIClass* spiPort).
  */
-#define USE_STANDARD_SPI_LIBRARY 0
+#ifndef USE_STANDARD_SPI_LIBRARY
+  #define USE_STANDARD_SPI_LIBRARY 0
+#endif
 //------------------------------------------------------------------------------
 /**
  * If the symbol ENABLE_SOFTWARE_SPI_CLASS is nonzero, the class SdFatSoftSpi
  * will be defined. If ENABLE_EXTENDED_TRANSFER_CLASS is also nonzero,
  * the class SdFatSoftSpiEX will be defined.
  */
-#define ENABLE_SOFTWARE_SPI_CLASS 0
+#ifndef ENABLE_SOFTWARE_SPI_CLASS
+  #define ENABLE_SOFTWARE_SPI_CLASS 0
+#endif
 //------------------------------------------------------------------------------
 /** If the symbol USE_FCNTL_H is nonzero, open flags for access modes O_RDONLY,
  * O_WRONLY, O_RDWR and the open modifiers O_APPEND, O_CREAT, O_EXCL, O_SYNC
@@ -112,14 +122,18 @@
  * Some cards will not sleep in low power mode unless CHECK_FLASH_PROGRAMMING
  * is non-zero.
  */
-#define CHECK_FLASH_PROGRAMMING 1
+#ifndef CHECK_FLASH_PROGRAMMING
+  #define CHECK_FLASH_PROGRAMMING 1
+#endif
 //------------------------------------------------------------------------------
 /**
  * Set MAINTAIN_FREE_CLUSTER_COUNT nonzero to keep the count of free clusters
  * updated.  This will increase the speed of the freeClusterCount() call
  * after the first call.  Extra flash will be required.
  */
-#define MAINTAIN_FREE_CLUSTER_COUNT 0
+#ifndef MAINTAIN_FREE_CLUSTER_COUNT
+  #define MAINTAIN_FREE_CLUSTER_COUNT 0
+#endif
 //------------------------------------------------------------------------------
 /**
  * To enable SD card CRC checking set USE_SD_CRC nonzero.
@@ -130,7 +144,9 @@
  * Set USE_SD_CRC to 2 to used a larger table driven CRC-CCITT function.  This
  * function is faster for AVR but may be slower for ARM and other processors.
  */
-#define USE_SD_CRC 0
+#ifndef USE_SD_CRC
+  #define USE_SD_CRC 0
+#endif
 //------------------------------------------------------------------------------
 /**
  * Handle Watchdog Timer for WiFi modules.
@@ -156,7 +172,9 @@
  *
  * Causes use of lots of heap in ARM.
  */
-#define DESTRUCTOR_CLOSES_FILE 0
+#ifndef DESTRUCTOR_CLOSES_FILE
+  #define DESTRUCTOR_CLOSES_FILE 0
+#endif
 //------------------------------------------------------------------------------
 /**
  * Call flush for endl if ENDL_CALLS_FLUSH is nonzero
@@ -175,7 +193,9 @@
  * If ENDL_CALLS_FLUSH is zero, you must call flush and/or close to force
  * all data to be written to the SD.
  */
-#define ENDL_CALLS_FLUSH 0
+#ifndef ENDL_CALLS_FLUSH
+  #define ENDL_CALLS_FLUSH 0
+#endif
 //------------------------------------------------------------------------------
 /**
  * Set USE_SEPARATE_FAT_CACHE nonzero to use a second 512 byte cache