Move decl of pulseInLong to the C++ section [...]

[...] of Arduino.h since it's implemented in C++.

CL: none

PUBLISHED_FROM=2687f4f16d3a54b9979e4c1651a6cb86d8cc41be

include/Arduino.h

@@ -136,9 +136,6 @@ void detachInterrupt(uint8_t pin);
 void interrupts(void);
 void noInterrupts(void);
 
-unsigned long pulseInLong(uint8_t pin, uint8_t state,
-    unsigned long timeout = 1000000L);
-
 void setup(void);
 void loop(void);
 
@@ -158,7 +155,12 @@ void loop(void);
 }  // extern "C"
 #endif
 
-#ifdef TODO
+#ifdef __cplusplus
+unsigned long pulseInLong(uint8_t pin, uint8_t state,
+                          unsigned long timeout = 1000000L);
+#endif
+
+#if 0 /* TODO */
 
 #ifdef __cplusplus