cmd/compile/internal/test: gofmt abiutils_test.go

Turns out that file is not formatted properly in the dev.regabi
branch.

Change-Id: I93125e65d5d3e8448c6ec1f077332c9bf7f0dd26
Reviewed-on: https://go-review.googlesource.com/c/go/+/292594
Trust: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Jeremy Faller <jeremy@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>

src/cmd/compile/internal/test/abiutils_test.go

@@ -292,4 +292,4 @@ func TestABINumParamRegs(t *testing.T) {
 	nrtest(t, s, 4)
 	nrtest(t, a, 12)
 
-}
+}