make constants static

Author: nerdralph

avr/cores/picocore/constants.h

@@ -1,10 +1,10 @@
 // global constants
 #include <stdint.h>
 
-const uint8_t LOW = 0;
-const uint8_t HIGH = 1;
-const uint8_t LED_BUILTIN = 2;
-const uint8_t NUM_DIGITAL_PINS = 6;
+static const uint8_t LOW = 0;
+static const uint8_t HIGH = 1;
+static const uint8_t LED_BUILTIN = 2;
+static const uint8_t NUM_DIGITAL_PINS = 6;
 
 typedef enum {MSBFIRST = 0, LSBFIRST} _bitOrder;