sys: time_units: add missing include

The header can't be fully used in standalone mode: toolchain.h has to be
included first, otherwise the ALWAYS_INLINE attribute is not defined.
Headers that can be directly included and are not self-contained should
be considered a bad practice.

Signed-off-by: Gerard Marull-Paretas <[email protected]>

Author: gmarull

include/sys/time_units.h

@@ -7,6 +7,9 @@
 #ifndef ZEPHYR_INCLUDE_TIME_UNITS_H_
 #define ZEPHYR_INCLUDE_TIME_UNITS_H_
 
+#include <sys/util.h>
+#include <toolchain.h>
+
 #ifdef __cplusplus
 extern "C" {
 #endif