Incompatible with remote exec via bazel-buildfarm

rules_foreign_cc fails on bazel-buildfarm workers. bazel-buildfarm enforces that inputs are read-only and directories are read/execute only. When rules_foreign_cc copies the directory tree, the permissions are preserved and subsequent ./configure commands that attempt to write Makefiles into these read-only directories will fail.

Start by locating the rules_foreign_cc logic that copies the input directory tree and trace how preserved permissions affect the subsequent ./configure step. Reproduce the failure on a bazel-buildfarm worker, then verify that configure can write Makefiles in the copied directories while the original inputs remain read-only.

Written by the indexing model from the issue text.