Upgrade to Qt 6 (#130)

Why? Open Source Qt 5 will stop receiving updates rather sooner than later so it's worth switching to Qt 6 to remain compatible with modern systems.

Reviewed-on: http://vub63vv26q6v27xzv2dtcd25xumubshogm67yrpaz2rculqxs7jlfqad.onion/torzu-emu/torzu/pulls/130

externals/clang_rt_builtins/udivti3.c

@@ -0,0 +1,36 @@
+typedef unsigned __int128 tu_int;
+
+tu_int __udivti3(tu_int a, tu_int b)
+{
+    if (b == 0) {
+        // Handle division by zero (could also trigger a fault)
+        return 0;
+    }
+
+    if (b > a) {
+        return 0;
+    }
+
+    int shift;
+    for (shift = 0;; shift++) {
+        if (shift >= 128) {
+            break;
+        }
+        tu_int shifted_b = b << shift;
+        if (shifted_b > a || (shifted_b >> shift) != b) {
+            break;
+        }
+    }
+    shift--;
+
+    tu_int quotient = 0;
+    for (; shift >= 0; shift--) {
+        tu_int shifted_b = b << shift;
+        if (shifted_b <= a) {
+            quotient |= (tu_int) 1 << shift;
+            a -= shifted_b;
+        }
+    }
+
+    return quotient;
+}