cmd/dist: avoid trailing space in instruction name strings

Change-Id: I2db4db852492eaddaf09dd7bae2fbd49f916e78a
Reviewed-on: https://go-review.googlesource.com/4648Reviewed-by: Rob Pike <r@golang.org>

src/cmd/dist/buildgc.go

@@ -87,7 +87,7 @@ func mkanames(dir, file string) {
 				line = line[:i]
 			}
 			line = line[2:]
-			fmt.Fprintf(&out, "\t\"%s\",\n", line)
+			fmt.Fprintf(&out, "\t\"%s\",\n", strings.TrimSpace(line))
 		}
 	}
 	fmt.Fprintf(&out, "};\n")