Remove PCH code: the code related to PCH is dead and not used (#66)

cherry-pick of compute/ec/clr/+/1184122

Co-authored-by: Juan Manuel Martinez Caamaño <juamarti@amd.com>

rocclr/platform/program.hpp

@@ -106,7 +106,6 @@ class Program : public RuntimeObject {
 
   std::vector<std::string> headerNames_;
   std::vector<std::string> headers_;
-  std::vector<std::string> precompiledHeaders_; //!< Precompiled Headers
   std::string sourceCode_;   //!< Strings that make up the source code
   Language language_;        //!< Input source language
   devicebinary_t binary_;    //!< The binary image, provided by the app
@@ -180,8 +179,6 @@ class Program : public RuntimeObject {
   //! Append to source code.
   void appendToSource(const char* newCode) { sourceCode_.append(newCode); }
 
-  void addPreCompiledHeader(const std::string& pch) { precompiledHeaders_.push_back(pch); }
-
   //! Return the program log.
   const std::string& programLog() const { return programLog_; }