runtime: move hash functions to newly created subproject

to reuse in compiler

common/build.gradle

@@ -0,0 +1,16 @@
+import org.jetbrains.kotlin.CompileCppToBitcode
+
+// TODO: consider using some Gradle plugins to build and test
+
+
+task compileHash(type: CompileCppToBitcode) {
+    name 'hash'
+}
+
+task build {
+    dependsOn compileHash
+}
+
+task clean << {
+    delete buildDir
+}