Unify incremental test cases and disable many

The self-hosted aarch64 backend is not currently functional due to the
Liveness changes. A previous commit disabled aarch64 on the behavior
tests; this commit disables it and arm for the test cases. Moreover, all
incremental test cases have been unified into shared cross-platform
cases, which can be gradually enabled as the backends improve.

test/cases/assert_function.12.zig

@@ -0,0 +1,47 @@
+pub fn main() void {
+    assert(add(3, 4) == 791);
+    assert(add(4, 3) == 79);
+}
+
+fn add(a: u32, b: u32) u32 {
+    const x: u32 = if (a < b) blk: {
+        const c = a + b; // 7
+        const d = a + c; // 10
+        const e = d + b; // 14
+        const f = d + e; // 24
+        const g = e + f; // 38
+        const h = f + g; // 62
+        const i = g + h; // 100
+        const j = i + d; // 110
+        const k = i + j; // 210
+        const l = k + c; // 217
+        const m = l + d; // 227
+        const n = m + e; // 241
+        const o = n + f; // 265
+        const p = o + g; // 303
+        const q = p + h; // 365
+        const r = q + i; // 465
+        const s = r + j; // 575
+        const t = s + k; // 785
+        break :blk t;
+    } else blk: {
+        const t = b + b + a; // 10
+        const c = a + t; // 14
+        const d = c + t; // 24
+        const e = d + t; // 34
+        const f = e + t; // 44
+        const g = f + t; // 54
+        const h = c + g; // 68
+        break :blk h + b; // 71
+    };
+    const y = x + a; // 788, 75
+    const z = y + a; // 791, 79
+    return z;
+}
+
+pub fn assert(ok: bool) void {
+    if (!ok) unreachable; // assertion failure
+}
+
+// run
+//