build: clean up config_fips.gypi

Currently when configuring the project using --openssl-fips a gyp
include file name config_fips.gypi will be created. If the project is
later configured but without the --openssl-fips flag an error will
occur. For example:

  $ ./configure --openssl-fips=bogus
  $ ./configure && make -j8
  ...
  /node/deps/openssl/fips/fipsld:
  line 8: /bin/fipsld: No such file or directory
  Error 127

This commit suggests removing the generate config_fips.gypi when the
--openssl-fips flag is not give on the command line.

PR-URL: #13837
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

configure

@@ -984,7 +984,10 @@ def configure_openssl(o):
     ]
   else:
     o['variables']['openssl_fips'] = ''
-
+    try:
+      os.remove('config_fips.gypi')
+    except OSError:
+      pass
 
   if options.without_ssl:
     def without_ssl_error(option):