Fix some -vet warnings; change import to core:math/bits

core/encoding/json/marshal.odin

@@ -1,7 +1,7 @@
 package json
 
 import "core:mem"
-import "core:bits"
+import "core:math/bits"
 import "core:runtime"
 import "core:strconv"
 import "core:strings"

core/encoding/json/tokenizer.odin

@@ -436,8 +436,8 @@ is_valid_string_literal :: proc(s: string, spec: Specification) -> bool {
 				i += 5;
 
 				for j := 0; j < 4; j += 1 {
-					c := hex[j];
-					switch c {
+					c2 := hex[j];
+					switch c2 {
 					case '0'..'9', 'a'..'z', 'A'..'Z':
 						// Okay
 					case:

core/encoding/json/types.odin

@@ -1,7 +1,5 @@
 package json
 
-import "core:strconv"
-
 Specification :: enum {
 	JSON,
 	JSON5,