Use auto-detected gcc host compiler include paths in CROSSTOOL file. (#4061)

This change removes the hard-coded cxx_builtin_include_directory entries and
instead generates cxx_builtin_include_directory entries using the compiler
include dirs detected using get_cxx_inc_directories.

This change also adds the auto_configure_fail function and uses it to improve
auto-configuration error messages.

Fixes #4058