Merge pull request #1905 from korli/haiku

Add Haiku support.
diff --git a/src/util.cc b/src/util.cc
index ae2e3c2..1e0d147 100644
--- a/src/util.cc
+++ b/src/util.cc
@@ -625,6 +625,10 @@
     return -0.0f;
   return 1.0 / (1 << SI_LOAD_SHIFT) * si.loads[0];
 }
+#elif defined(__HAIKU__)
+double GetLoadAverage() {
+    return -0.0f;
+}
 #else
 double GetLoadAverage() {
   double loadavg[3] = { 0.0f, 0.0f, 0.0f };