Obsequi: Use ANSI C LCG instead of random() for g_zobrist init

musl implements random() differently than glibc.

The output of the program is thus dependent on this implementation
detail and could differ between platforms. To remediate that, we
replace it by a very simple PRNG (ANSI C LCG).

Warning: [^1] indicates this PRNG have quite a poor LSB randomness.

[^1]: Entacher, Karl. (1999). A Collection of Selected Pseudorandom
Number Generators With Linear Structures.

Fixes llvm/llvm-project#94048

Author: v01dxyz

MultiSource/Applications/obsequi/Obsequi.reference_output

@@ -136,10 +136,10 @@ alpha 0, beta 5000.
 cutoffs depth 1: (56) 0 - 0 0 0 0 0 >0.
 The value is -5 at a depth of 1.
 Nodes: 56.
-Move (2,1), value 5000: 2,023,301.
+Move (2,1), value 5000: 2,023,432.
 alpha -5000, beta 5000.
 Winner found: 5000.
-1356 2450 1316053 104829.
+1356 2449 1316027 104839.
 
 cutoffs depth 1: (1) 0 - 0 0 0 0 0 >0.
 cutoffs depth 2: (52) 52 - 52 0 0 0 0 >0.
@@ -148,19 +148,19 @@ cutoffs depth 4: (1263) 728 - 728 0 0 0 0 >0.
 cutoffs depth 5: (728) 0 - 0 0 0 0 0 >0.
 cutoffs depth 6: (21651) 9812 - 9810 1 1 0 0 >0.
 cutoffs depth 7: (9815) 3 - 2 0 0 0 1 >0.
-cutoffs depth 8: (160368) 38732 - 38714 14 4 0 0 >0.
-cutoffs depth 9: (38807) 50 - 39 6 5 0 0 >0.
-cutoffs depth 10: (631941) 86758 - 86673 52 10 2 2 >19.
-cutoffs depth 11: (87924) 775 - 634 85 19 21 10 >6.
-cutoffs depth 12: (771767) 55353 - 54840 256 82 15 64 >96.
-cutoffs depth 13: (64920) 3921 - 3389 387 124 16 5 >0.
-cutoffs depth 14: (187771) 7691 - 6649 766 123 44 105 >4.
-cutoffs depth 15: (24493) 3183 - 2950 210 13 7 3 >0.
-cutoffs depth 16: (14596) 1814 - 1786 26 0 0 2 >0.
-cutoffs depth 17: (5052) 559 - 523 33 3 0 0 >0.
+cutoffs depth 8: (160464) 38725 - 38707 14 4 0 0 >0.
+cutoffs depth 9: (38800) 50 - 39 6 5 0 0 >0.
+cutoffs depth 10: (631893) 86794 - 86709 52 10 2 2 >19.
+cutoffs depth 11: (87960) 775 - 634 85 19 21 10 >6.
+cutoffs depth 12: (771839) 55370 - 54856 257 82 15 64 >96.
+cutoffs depth 13: (64938) 3921 - 3389 387 124 16 5 >0.
+cutoffs depth 14: (187745) 7681 - 6638 767 123 44 105 >4.
+cutoffs depth 15: (24484) 3183 - 2950 210 13 7 3 >0.
+cutoffs depth 16: (14596) 1813 - 1785 26 0 0 2 >0.
+cutoffs depth 17: (5051) 559 - 523 33 3 0 0 >0.
 cutoffs depth 18: (1699) 181 - 167 9 5 0 0 >0.
 cutoffs depth 19: (326) 34 - 34 0 0 0 0 >0.
 cutoffs depth 20: (73) 2 - 2 0 0 0 0 >0.
 cutoffs depth 21: (2) 0 - 0 0 0 0 0 >0.
-winner V, move (1,2), nodes 2,023,301.
+winner V, move (1,2), nodes 2,023,432.
 exit 0

MultiSource/Applications/obsequi/init.c

@@ -49,6 +49,10 @@ init__real_count(s32bit player)
   }
 }
 
+static s32bit ansi_c_lcg(s32bit x) {
+  return (1103515245*x + 12345) & 0x7fffffff;
+}
+
 extern void
 initialize_solver()
 {
@@ -60,10 +64,11 @@ initialize_solver()
     g_trans_table = calloc(HASHSIZE,sizeof(Hash_Entry));
 
     // initialize zobrist values
-    srandom(1);
+    s32bit r = 1;
     for(i=1; i<31; i++) {
       for(j=1; j<31; j++) {
-        g_zobrist[i][j] = random() & HASHMASK;
+        r = ansi_c_lcg(r);
+        g_zobrist[i][j] = r & HASHMASK;
       }
     }