builtin: use single line imports, to make analysis easier

vlib/builtin/array.v

@@ -3,9 +3,7 @@
 // that can be found in the LICENSE file.
 module builtin
 
-import (
-	strings
-)
+import strings
 
 pub struct array {
 pub:

vlib/builtin/bare/syscallwrapper_test.v

@@ -1,6 +1,4 @@
-import (
-	os
-)
+import os
 
 fn test_syscallwrappers() {
 	if true { return }

vlib/builtin/float.v

@@ -3,9 +3,7 @@
 // that can be found in the LICENSE file.
 module builtin
 
-import (
-	strconv.ftoa
-)
+import strconv.ftoa
 
 #include <float.h>
 // ----- f64 to string functions -----

vlib/builtin/map.v

@@ -3,10 +3,8 @@
 // that can be found in the LICENSE file.
 module builtin
 
-import (
-	strings
-	hash.wyhash
-)
+import strings
+import hash.wyhash
 
 fn C.memcmp(byteptr, byteptr, int) int