Update due to newer gcc being more pendantic about constexpr. (#845)
Update due to newer gcc being more pendantic about constexpr. (#845)

Specifically, cannot cast integer values to pointers in a constexpr,
requiring use of intptr_t in the constexpr.  Callers of the constexpr
may then cast it at the non-constexpr location of use.

See https://stackoverflow.com/questions/10369606/constexpr-pointer-value
PaulStoffregen/FastLED,FastLED/FastLED,FastLED/FastLED,PaulStoffregen/FastLED,FastLED/FastLED,FastLED/FastLED,PaulStoffregen/FastLED