Remove builds conditional on go1.7 since that is now guaranteed #2154

Old fallback code was deleted and the go1.7 style code inlined where
appropriate.

backend/cache/cache.go

@@ -1,4 +1,4 @@
-// +build !plan9,go1.7
+// +build !plan9
 
 package cache
 

backend/cache/cache_internal_test.go

@@ -1,4 +1,4 @@
-// +build !plan9,go1.7
+// +build !plan9
 
 package cache_test
 

backend/cache/cache_mount_unix_test.go

@@ -1,4 +1,4 @@
-// +build !plan9,!windows,go1.7
+// +build !plan9,!windows
 
 package cache_test
 

backend/cache/cache_mount_windows_test.go

@@ -1,4 +1,4 @@
-// +build windows,go1.7
+// +build windows
 
 package cache_test
 

backend/cache/cache_test.go

@@ -3,7 +3,7 @@
 // Automatically generated - DO NOT EDIT
 // Regenerate with: make gen_tests
 
-// +build !plan9,go1.7
+// +build !plan9
 
 package cache_test
 

backend/cache/cache_unsupported.go

@@ -1,6 +1,6 @@
 // Build for cache for unsupported platforms to stop go complaining
 // about "no buildable Go source files "
 
-// +build plan9 !go1.7
+// +build plan9
 
 package cache

backend/cache/directory.go

@@ -1,4 +1,4 @@
-// +build !plan9,go1.7
+// +build !plan9
 
 package cache
 

backend/cache/handle.go

@@ -1,4 +1,4 @@
-// +build !plan9,go1.7
+// +build !plan9
 
 package cache
 

backend/cache/object.go

@@ -1,4 +1,4 @@
-// +build !plan9,go1.7
+// +build !plan9
 
 package cache
 

backend/cache/plex.go

@@ -1,4 +1,4 @@
-// +build !plan9,go1.7
+// +build !plan9
 
 package cache
 

backend/cache/storage_memory.go

@@ -1,4 +1,4 @@
-// +build !plan9,go1.7
+// +build !plan9
 
 package cache
 

backend/cache/storage_persistent.go

@@ -1,4 +1,4 @@
-// +build !plan9,go1.7
+// +build !plan9
 
 package cache