[ruby] fixing path to gcc such that users can use gem to install nati… (#17141)

* [ruby] fixing path to gcc such that users can use gem to install native gems to their home directory

* [ruby] working on making flake8 happier

* [ruby] Line can't really be split cleanly. Enhancing flake8's calm.

ya learn something new every day...

* [ruby] line break where requested

* [ruby] make raw string

* [ruby] only running for x86_64-linux everything else is untested

* [ruby] finding rbconfig.rb in a cross platform manner

var/spack/repos/builtin/packages/ruby/package.py

@@ -114,3 +114,14 @@ def post_install(self):
                                             'rubygems',
                                             'ssl_certs')
             install(rubygems_updated_cert_path, rubygems_certs_path)
+
+        rbconfig = find(self.prefix, 'rbconfig.rb')[0]
+        filter_file(r'^(\s*CONFIG\["CXX"\]\s*=\s*).*',
+                    r'\1"{0}"'.format(self.compiler.cxx),
+                    rbconfig)
+        filter_file(r'^(\s*CONFIG\["CC"\]\s*=\s*).*',
+                    r'\1"{0}"'.format(self.compiler.cc),
+                    rbconfig)
+        filter_file(r'^(\s*CONFIG\["MJIT_CC"\]\s*=\s*).*',
+                    r'\1"{0}"'.format(self.compiler.cc),
+                    rbconfig)