allow local variable address detection to regress

See #3180 for a more comprehensive plan to catch this problem. More
sophisticated control flow analysis is needed to provide compile errors
for returning local variable addresses from a function.

Author: andrewrk

test/compile_errors.zig

@@ -5292,25 +5292,6 @@ pub fn addCases(cases: *tests.CompileErrorContext) void {
         "tmp.zig:2:30: error: cannot set section of local variable 'foo'",
     });
 
-    cases.add("returning address of local variable - simple",
-        \\export fn foo() *i32 {
-        \\    var a: i32 = undefined;
-        \\    return &a;
-        \\}
-    , &[_][]const u8{
-        "tmp.zig:3:13: error: function returns address of local variable",
-    });
-
-    cases.add("returning address of local variable - phi",
-        \\export fn foo(c: bool) *i32 {
-        \\    var a: i32 = undefined;
-        \\    var b: i32 = undefined;
-        \\    return if (c) &a else &b;
-        \\}
-    , &[_][]const u8{
-        "tmp.zig:4:12: error: function returns address of local variable",
-    });
-
     cases.add("inner struct member shadowing outer struct member",
         \\fn A() type {
         \\    return struct {