Remove unused `PHI` define in math funcs

core/math/math_funcs.cpp

@@ -34,8 +34,6 @@
 
 RandomPCG Math::default_rand(RandomPCG::DEFAULT_SEED, RandomPCG::DEFAULT_INC);
 
-#define PHI 0x9e3779b9
-
 uint32_t Math::rand_from_seed(uint64_t *seed) {
 	RandomPCG rng = RandomPCG(*seed, RandomPCG::DEFAULT_INC);
 	uint32_t r = rng.rand();