Added benchmark skeleton, and at least stubs for all of the necessary functions

src/t_benchmark.c

@@ -0,0 +1,14 @@
+// At this point, this is just a compile/link test.
+#include "hammer.h"
+
+HParserTestcase testcases[] = {
+  {NULL, 0, NULL}
+};
+
+void test_benchmark_1() {
+  HParser *parser = NULL; // TODO: fill this in.
+
+  HBenchmarkResults *res = h_benchmark(parser, testcases);
+  h_benchmark_report(stderr, res);
+
+}