examples/geohash: first version

Adds helper for constants as DATA sections.

examples/geohash/geohash_test.go

@@ -0,0 +1,13 @@
+package geohash
+
+import (
+	"testing"
+)
+
+//go:generate go run asm.go -out geohash.s -stubs stub.go
+
+func TestEncodeIntMountEverest(t *testing.T) {
+	if EncodeInt(27.988056, 86.925278) != 0xceb7f254240fd612 {
+		t.Fail()
+	}
+}