Fixes first pixel not being set in Stream FX (#4542)

* Fixes first pixel not being set
* added fix to Stream 2 as well

Author: DedeHai

wled00/FX.cpp

@@ -1091,7 +1091,7 @@ uint16_t mode_running_random(void) {
 
   unsigned z = it % zoneSize;
   bool nzone = (!z && it != SEGENV.aux1);
-  for (unsigned i=SEGLEN-1; i > 0; i--) {
+  for (int i=SEGLEN-1; i >= 0; i--) {
     if (nzone || z >= zoneSize) {
       unsigned lastrand = PRNG16 >> 8;
       int16_t diff = 0;
@@ -1739,7 +1739,7 @@ uint16_t mode_random_chase(void) {
   uint32_t color = SEGENV.step;
   random16_set_seed(SEGENV.aux0);
 
-  for (unsigned i = SEGLEN -1; i > 0; i--) {
+  for (int i = SEGLEN -1; i >= 0; i--) {
     uint8_t r = random8(6) != 0 ? (color >> 16 & 0xFF) : random8();
     uint8_t g = random8(6) != 0 ? (color >> 8  & 0xFF) : random8();
     uint8_t b = random8(6) != 0 ? (color       & 0xFF) : random8();