Use the same platform for quicksort and shared-quicksort

examples/shared-quicksort/platform/build.sh

@@ -0,0 +1,12 @@
+#!/bin/bash
+
+# compile c_host.o and rust_host.o
+clang -c host.c -o c_host.o
+rustc host.rs -o rust_host.o
+
+# link them together into host.o
+ld -r c_host.o rust_host.o -o host.o
+
+# clean up
+rm -f c_host.o
+rm -f rust_host.o