Switch to stdbool.h

- Add `#include <stdbool.h> to all files previously using the
   `TRUE`/`FALSE` macros
 - Replace all instances of `TRUE`/`FALSE` with `true`/`false`,
   respectively
 - Definitions of `TRUE`/`FALSE` macros retained in wiringPi.h for compatibility.

wiringPi/max5322.c

@@ -22,6 +22,8 @@
  ***********************************************************************
  */
 
+#include <stdbool.h>
+
 #include <wiringPi.h>
 #include <wiringPiSPI.h>
 
@@ -66,7 +68,7 @@ int max5322Setup (const int pinBase, int spiChannel)
   unsigned char spiData [2] ;
 
   if (wiringPiSPISetup (spiChannel, 8000000) < 0)	// 10MHz Max
-    return FALSE ;
+    return false ;
 
   node = wiringPiNewNode (pinBase, 2) ;
 
@@ -80,5 +82,5 @@ int max5322Setup (const int pinBase, int spiChannel)
   
   wiringPiSPIDataRW (node->fd, spiData, 2) ;
 
-  return TRUE ;
+  return true ;
 }