Changed import path to operating_systems

lib/spack/spack/platforms/bgq.py

@@ -1,5 +1,4 @@
 import os
-
 from spack.architecture import Platform, Target
 
 class Bgq(Platform):

lib/spack/spack/platforms/cray_xc.py

@@ -1,7 +1,7 @@
 import os
 from spack.architecture import Platform, Target
-from spack.operating_system.linux_distro import LinuxDistro
-from spack.operating_system.cnl import Cnl
+from spack.operating_systems.linux_distro import LinuxDistro
+from spack.operating_systems.cnl import Cnl
 
 class CrayXc(Platform):
     priority    = 20

lib/spack/spack/platforms/darwin.py

@@ -1,6 +1,6 @@
 import subprocess
 from spack.architecture import Platform, Target
-from spack.operating_system.mac_osx import MacOsx
+from spack.operating_systems.mac_osx import MacOsx
 
 class Darwin(Platform):
     priority    = 89

lib/spack/spack/platforms/linux.py

@@ -1,6 +1,6 @@
 import subprocess
 from spack.architecture import Platform, Target
-from spack.operating_system.linux_distro import LinuxDistro
+from spack.operating_systems.linux_distro import LinuxDistro
 
 class Linux(Platform):
     priority    = 90