Add test for optimizing first-class view operation

doc/allopts.txt

@@ -30,6 +30,7 @@ local misc
     combine adjacent loads/stores
     byteswap recognition
     reorder bounds checks of a[0], a[1], a[2]...
+    ordering of strength-reduction and direct call recording (inlining)
 
 local control flow optimizations
   * branch folding

test/core/opt_view00.v3

@@ -0,0 +1,6 @@
+//@execute 0=0; 1=1; 256=1; 65537=2; 16909060=10
+def main(x: int) -> int {
+	def u = u8.view<int>;
+	var a = u(x >> 0), b = u(x >> 8), c = u(x >> 16), d = u(x >> 24);
+	return a + b + c + d;
+}