Merge bitcoin-core/secp256k1#1285: bench: Make sys/time.h a system include

68b16a1 bench: Make sys/time.h a system include (Tim Ruffing)

Pull request description:

  just because it is minimally more correct

ACKs for top commit:
  hebasto:
    ACK 68b16a1, I've skimmed through the whole codebase and did not find any more similar cases.

Tree-SHA512: 0a929b36202100abf0d14e9328a2dc2b4c9db5532f95514315cb04dd0a970dbbb1dc02c6275be0ec109dc88f6090f6ce48a65003c852fd4dc750decf07e563c4

Author: real-or-random

src/bench.h

@@ -15,7 +15,7 @@
 #if (defined(_MSC_VER) && _MSC_VER >= 1900)
 #  include <time.h>
 #else
-#  include "sys/time.h"
+#  include <sys/time.h>
 #endif
 
 static int64_t gettime_i64(void) {