init: add host side parser for init

Create a host side parser for init such that init rc files can be
verified for syntax correctness before being used on the device.

Bug: 36970783
Test: run the parser on init files on host

Change-Id: I7e8772e278ebaff727057308596ebacf28b6fdda
diff --git a/init/parser.h b/init/parser.h
index 110a468..f6e237f 100644
--- a/init/parser.h
+++ b/init/parser.h
@@ -72,13 +72,14 @@
     Parser();
 
     bool ParseConfig(const std::string& path);
+    bool ParseConfig(const std::string& path, size_t* parse_errors);
     void AddSectionParser(const std::string& name, std::unique_ptr<SectionParser> parser);
     void AddSingleLineParser(const std::string& prefix, LineCallback callback);
 
   private:
-    void ParseData(const std::string& filename, const std::string& data);
-    bool ParseConfigFile(const std::string& path);
-    bool ParseConfigDir(const std::string& path);
+    void ParseData(const std::string& filename, const std::string& data, size_t* parse_errors);
+    bool ParseConfigFile(const std::string& path, size_t* parse_errors);
+    bool ParseConfigDir(const std::string& path, size_t* parse_errors);
 
     std::map<std::string, std::unique_ptr<SectionParser>> section_parsers_;
     std::vector<std::pair<std::string, LineCallback>> line_callbacks_;