timeutil: remove detritus windows Now() implementation

We carried a custom implementation of timeutil.Now() for Windows, to
overcome the low precision of Go's impl [1]. It was doing so with an
expensive implementation. Having this custom implementation also make it
tricky to use stdlib functions like Since(), which internally use the
stdlib Now().
The Golang issue has since been fixed.

[1] golang/go#8687

Release note: None

pkg/testutils/lint/lint_test.go

@@ -723,8 +723,6 @@ func TestLint(t *testing.T) {
 			"--",
 			"*.go",
 			":!**/embedded.go",
-			":!util/timeutil/now_unix.go",
-			":!util/timeutil/now_windows.go",
 			":!util/timeutil/time.go",
 			":!util/timeutil/zoneinfo.go",
 			":!util/tracing/span.go",

pkg/util/timeutil/BUILD.bazel

@@ -4,8 +4,6 @@ go_library(
     name = "timeutil",
     srcs = [
         "manual_time.go",
-        "now_unix.go",
-        "now_windows.go",
         "stopwatch.go",
         "time.go",
         "time_source.go",
@@ -20,12 +18,7 @@ go_library(
     deps = [
         "//pkg/util/syncutil",
         "@com_github_cockroachdb_errors//:errors",
-    ] + select({
-        "@io_bazel_rules_go//go/platform:windows": [
-            "@org_golang_x_sys//windows",
-        ],
-        "//conditions:default": [],
-    }),
+    ],
 )
 
 go_test(

pkg/util/timeutil/time.go

@@ -18,6 +18,11 @@ import (
 // LibPQTimePrefix is the prefix lib/pq prints time-type datatypes with.
 const LibPQTimePrefix = "0000-01-01"
 
+// Now returns the current UTC time.
+func Now() time.Time {
+	return time.Now().UTC()
+}
+
 // Since returns the time elapsed since t.
 // It is shorthand for Now().Sub(t).
 func Since(t time.Time) time.Duration {