Merge pull request #55 from caternuson/hw_spi_fix

Fix HW SPI preprocessor check

Author: caternuson

Adafruit_DotStar.h

@@ -101,7 +101,9 @@ static const uint8_t PROGMEM _DotStarGammaTable[256] = {
 class Adafruit_DotStar {
 
 public:
-#if defined SPI // Is a default hardware SPI device defined for this board?
+#if !defined(SPI_INTERFACES_COUNT) ||                                          \
+    (defined(SPI_INTERFACES_COUNT) && (SPI_INTERFACES_COUNT > 0))
+  // HW SPI available
   Adafruit_DotStar(uint16_t n, uint8_t o = DOTSTAR_BRG, SPIClass *spi = &SPI);
 #else
   Adafruit_DotStar(uint16_t n, uint8_t o = DOTSTAR_BRG, SPIClass *spi = NULL);