Fix solaris build. (#6149)

* Fix solaris build.
* Tidy up build constraints on statfs_linux_386.go
Signed-off-by: NPeter Tribble <peter.tribble@gmail.com>

pkg/runtime/statfs.go

@@ -11,7 +11,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// +build openbsd windows netbsd
+// +build openbsd windows netbsd solaris
 
 package runtime
 

pkg/runtime/statfs_default.go

@@ -11,7 +11,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// +build !windows,!openbsd,!netbsd
+// +build !windows,!openbsd,!netbsd,!solaris
 // +build !386
 
 package runtime

pkg/runtime/statfs_linux_386.go

@@ -11,7 +11,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// +build !windows !openbsd !darwin !freebsd !netbsd
 // +build linux,386
 
 package runtime