cmd/compile: emit definition of 'any' only if generic enabled

CL 364377 emitted definition of 'any' when compiling runtime. But 'any'
is only available when generic enabled. Thus emitting its definition
unconditionally causes the compiler crashes.

Updates #49619

Change-Id: I0888ca1cbc7a7df300310a99a344f170636333f2
Reviewed-on: https://go-review.googlesource.com/c/go/+/364614
Trust: Cuong Manh Le <[email protected]>
Trust: Dan Scales <[email protected]>
Run-TryBot: Cuong Manh Le <[email protected]>
TryBot-Result: Go Bot <[email protected]>
Reviewed-by: Dan Scales <[email protected]>

Author: cuonglm

src/cmd/compile/internal/reflectdata/reflect.go

@@ -1384,7 +1384,9 @@ func WriteBasicTypes() {
 		}
 		writeType(types.NewPtr(types.Types[types.TSTRING]))
 		writeType(types.NewPtr(types.Types[types.TUNSAFEPTR]))
-		writeType(types.AnyType)
+		if base.Flag.G > 0 {
+			writeType(types.AnyType)
+		}
 
 		// emit type structs for error and func(error) string.
 		// The latter is the type of an auto-generated wrapper.

test/fixedbugs/issue49619.go

@@ -1,4 +1,4 @@
-// build
+// build -gcflags=-G=3
 
 // Copyright 2021 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style