Merge pull request #2009 from yshui/musl_libc_src_core_sys_posix_sys_time

 Add musl libc definitions to:  src_core_sys_posix_sys_time
merged-on-behalf-of: Iain Buclaw <ibuclaw@gdcproject.org>

Author: dlang-bot

src/core/sys/posix/sys/time.d

@@ -82,6 +82,15 @@ version( CRuntime_Glibc )
     int setitimer(int, in itimerval*, itimerval*);
     int utimes(in char*, ref const(timeval)[2]); // LEGACY
 }
+else version( CRuntime_Musl )
+{
+    struct timeval
+    {
+        time_t      tv_sec;
+        suseconds_t tv_usec;
+    }
+    int gettimeofday(timeval*, void*);
+}
 else version( Darwin )
 {
     struct timeval