Add BPF-to-BPF and PC relative call tests (#2395)

programs/bpf/c/src/relative_call/relative_call.c

@@ -0,0 +1,16 @@
+/**
+ * @brief test program that generates BPF PC relative call instructions
+ */
+
+#include <solana_sdk.h>
+
+void __attribute__ ((noinline)) helper() {
+  sol_log(__func__);
+}
+
+extern bool entrypoint(const uint8_t *input) {
+  sol_log(__func__);
+  helper();
+  return true;
+}
+