Give time.h a title and move to low-level infra group

Change-Id: I4cb50bda726fcc0f22fcb53dca92cf297aeea169
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/64929
Commit-Queue: David Benjamin <davidben@google.com>
Reviewed-by: Bob Beck <bbe@google.com>
diff --git a/include/openssl/time.h b/include/openssl/time.h
index 723ce10..50db22d 100644
--- a/include/openssl/time.h
+++ b/include/openssl/time.h
@@ -23,6 +23,10 @@
 extern "C" {
 #endif
 
+
+// Time functions.
+
+
 // OPENSSL_posix_to_tm converts a int64_t POSIX time value in |time|, which must
 // be in the range of year 0000 to 9999, to a broken out time value in |tm|. It
 // returns one on success and zero on error.