tests/capi: dump Lua samples

mkdir /tmp/corpus
RUNS=1 ctest -R luaL_loadbuffer_proto_test --verbose

/home/sergeyb/sources/lua-c-api-tests/build/tests/capi/luaL_loadbuffer_proto/luaL_loadbuffer_proto_test -print_final_stats=1 -print_pcs=1 -reduce_inputs=1 -reload=1 -runs=1 -workers=22  -timeout=5 -jobs=5 /home/sergeyb/sources/lua-c-api-tests/corpus/corpus/luaL_loadbuffer_proto_test

LUA_FUZZER_VERBOSE=1 LPM_DUMP_NATIVE_INPUT=1 /home/sergeyb/sources/lua-c-api-tests/build/tests/capi/luaL_loadbuffer_proto/luaL_loadbuffer_proto_test -print_final_stats=1 -print_pcs=1 -reduce_inputs=1 -reload=1 -runs=1 -workers=22  -timeout=5 /home/sergeyb/sources/lua-c-api-tests/corpus/corpus/luaL_loadbuffer_proto_test 2>&1 | tee log.txt

```
mkdir /tmp/lua-corpus/
go install github.com/yuin/gopher-lua/cmd/glua
stat $GOPATH/bin/glua
for f in /tmp/lua-corpus/*; do echo $f; glua $f; done
```

Author: ligurio

tests/capi/luaL_loadbuffer_proto/luaL_loadbuffer_proto_test.cc

@@ -5,6 +5,10 @@
  * Copyright 2022, Tarantool AUTHORS.
  */
 
+#include <fstream>
+#include <string>
+#include <iostream>
+
 extern "C"
 {
 #include "lua.h"
@@ -304,6 +308,11 @@ DEFINE_PROTO_FUZZER(const lua_grammar::Block &message)
 	luaJIT_profile_dumpstack(L, "pfFlz", len, &depth);
 #endif /* LUAJIT */
 
+	std::size_t hash = std::hash<std::string>{}(code);
+	std::ofstream out("/tmp/corpus/" + std::to_string(hash) + ".lua");
+	out << code;
+	out.close();
+
 	if (luaL_loadbuffer(L, code.c_str(), code.size(), "fuzz") != LUA_OK) {
 		report_error(L, "luaL_loadbuffer()");
 		goto end;