Add support for embedding LuaJIT bytecode for builtins.

src/host/buildvm_libbc.h

@@ -0,0 +1,12 @@
+/* This is a generated file. DO NOT EDIT! */
+
+static const int libbc_endian = 0;
+
+static const uint8_t libbc_code[] = {
+0
+};
+
+static const struct { const char *name; int ofs; } libbc_map[] = {
+{NULL,0}
+};
+