cmd/compile: add reflect to TestIntendedInlining

Add the package to the table and start it off with a few small, basic
functions. Inspired by CL 66331, which added flag.ro.

Updates #21851.

Change-Id: I3995cde1ff7bb09a718110473bed8b193c2232a5
Reviewed-on: https://go-review.googlesource.com/66990
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ilya Tocar <ilya.tocar@intel.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/cmd/compile/internal/gc/inl_test.go

@@ -113,6 +113,23 @@ func TestIntendedInlining(t *testing.T) {
 			"RuneLen",
 			"ValidRune",
 		},
+		"reflect": {
+			"Value.CanAddr",
+			"Value.CanSet",
+			"Value.IsValid",
+			"add",
+			"align",
+			"flag.kind",
+			"flag.ro",
+
+			// TODO: these use panic, need mid-stack
+			// inlining
+			// "Value.CanInterface",
+			// "Value.pointer",
+			// "flag.mustBe",
+			// "flag.mustBeAssignable",
+			// "flag.mustBeExported",
+		},
 		"regexp": {
 			"(*bitState).push",
 		},