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Remove broken pseudo-random algorithm

Caused undefined behavior on left-shift overflow. This could lead to
either code-erasure by compiler or garbage data left in a register,
possibly corrupting heap.

--- a/tui_main.c

+++ b/tui_main.c

@@ -771,42 +771,6 @@

   Usz random_seed;

 } Ged;

-// for initializing random, unsed in ged_init

-// http://www.concentric.net/~Ttwang/tech/inthash.htm

-Usz random_seed_mix(void) {

-  Isz a = (Isz)clock();

-  Isz b = (Isz)time(NULL);

-  Isz c = (Isz)getpid();

-  a = a - b;

-  a = a - c;

-  a = a ^ (c >> 13);

-  b = b - c;

-  b = b - a;

-  b = b ^ (a << 8);

-  c = c - a;

-  c = c - b;

-  c = c ^ (b >> 13);

-  a = a - b;

-  a = a - c;

-  a = a ^ (c >> 12);

-  b = b - c;

-  b = b - a;

-  b = b ^ (a << 16);

-  c = c - a;

-  c = c - b;

-  c = c ^ (b >> 5);

-  a = a - b;

-  a = a - c;

-  a = a ^ (c >> 3);

-  b = b - c;

-  b = b - a;

-  b = b ^ (a << 10);

-  c = c - a;

-  c = c - b;

-  c = c ^ (b >> 15);

-  return (Usz)c;

-}

-

 void ged_init(Ged* a, Usz undo_limit, Usz init_bpm) {

   field_init(&a->field);

   field_init(&a->scratch_field);

@@ -844,7 +808,7 @@

   a->is_mouse_down = false;

   a->is_mouse_dragging = false;

   a->is_hud_visible = false;

-  a->random_seed = random_seed_mix();

+  a->random_seed = 1;

 }

 void ged_deinit(Ged* a) {