Do not include time.h without MBEDTLS_HAVE_TIME

MBEDTLS_HAVE_TIME is documented as: "System has time.h and time()."

If that is not defined, do not attempt to include time.h.

A particular problem is platform-time.h, which should only be included if
MBEDTLS_HAVE_TIME is defined, which makes everything messier. Maybe it
should be refactored to have the check inside the header.

Signed-off-by: Daniel Axtens <dja@axtens.net>
diff --git a/library/x509_crl.c b/library/x509_crl.c
index ac4fc75..d2d8042 100644
--- a/library/x509_crl.c
+++ b/library/x509_crl.c
@@ -52,11 +52,13 @@
 #define mbedtls_snprintf   snprintf
 #endif
 
+#if defined(MBEDTLS_HAVE_TIME)
 #if defined(_WIN32) && !defined(EFIX64) && !defined(EFI32)
 #include <windows.h>
 #else
 #include <time.h>
 #endif
+#endif
 
 #if defined(MBEDTLS_FS_IO) || defined(EFIX64) || defined(EFI32)
 #include <stdio.h>