Add 'RemoteBuildPlatform' to installed metadata

This is useful to decide what platform a package was
installed on.

R/install-binary.R

@@ -61,7 +61,9 @@ install_extracted_binary <- function(filename, lib_cache, pkg_cache, lib,
 
 #' @importFrom utils modifyList
 add_metadata <- function(pkg_path, metadata) {
-  if (!length(metadata)) return()
+  if (! "RemoteBuildPlatform" %in% names(metadata)) {
+    metadata[["RemoteBuildPlatform"]] <- current_r_platform()
+  }
 
   ## During installation, the DESCRIPTION file is read and an package.rds
   ## file created with most of the information from the DESCRIPTION file.