Flesh out a page size accessor in the new API.

Implement the old API in terms of the new one. This simplifies the
implementation on Windows which can now re-use the self_process's once
initialization.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@171330 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Support/Process.h

@@ -89,7 +89,27 @@ class self_process : public process {
 public:
   virtual id_type get_id();
 
+  /// \name Process configuration (sysconf on POSIX)
+  /// @{
+
+  /// \brief Get the virtual memory page size.
+  ///
+  /// Query the operating system for this process's page size.
+  size_t page_size() const { return PageSize; };
+
+  /// @}
+
 private:
+  /// \name Cached process state.
+  /// @{
+
+  /// \brief Cached page size, this cannot vary during the life of the process.
+  size_t PageSize;
+
+  /// @}
+
+  /// \brief Constructor, used by \c process::get_self() only.
+  self_process();
 };