cmd/go: remove unnecessary else conditions

Fixes golint warning about "if block ends with a return statement, so drop this else and outdent its block".

Change-Id: I6fc8724f586efcb6e2ed92ee36be421d3e9a8c80
Reviewed-on: https://go-review.googlesource.com/c/144137Reviewed-by: Ralph Corderoy <ralph@inputplus.co.uk>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/cmd/go/internal/semver/semver.go

@@ -312,9 +312,8 @@ func compareInt(x, y string) int {
 	}
 	if x < y {
 		return -1
-	} else {
-		return +1
 	}
+	return +1
 }
 
 func comparePrerelease(x, y string) int {
@@ -353,9 +352,8 @@ func comparePrerelease(x, y string) int {
 			if ix != iy {
 				if ix {
 					return -1
-				} else {
-					return +1
 				}
+				return +1
 			}
 			if ix {
 				if len(dx) < len(dy) {
@@ -367,16 +365,14 @@ func comparePrerelease(x, y string) int {
 			}
 			if dx < dy {
 				return -1
-			} else {
-				return +1
 			}
+			return +1
 		}
 	}
 	if x == "" {
 		return -1
-	} else {
-		return +1
 	}
+	return +1
 }
 
 func nextIdent(x string) (dx, rest string) {