Merge #10: Remove #include <syscall.h> to avoid mac os build error

4e452e9 Remove #include <syscall.h> to avoid mac os build error (Russell Yanofsky)

Pull request description:

  Issue was found by hugohn in #5 (comment)

Top commit has no ACKs.

Tree-SHA512: 2e080af28bc1e21b07b4c2768bea43c768daa9bfba1bfb76d1b45cfd414796de9c1e9f81f30ad16a85c356e7037d7b576b3fd9e9430e27b8b64fe2e3437e532a

Author: ryanofsky

src/mp/util.cpp

@@ -13,9 +13,12 @@
 #include <sys/types.h>
 #include <sys/un.h>
 #include <sys/wait.h>
-#include <syscall.h>
 #include <unistd.h>
 
+#if __linux__
+#include <syscall.h>
+#endif
+
 namespace mp {
 namespace {