Ruby

mkmf: Add the extra option --with-verbose to enable verbose mode. (#7863)

This commit is to add an extra option to enable verbose mode (V=1) in the
generated Makefile at runtime of the Ruby to print compiler command lines by
the commands below when building native extensions. It's possible to enable the
verbose mode by setting the environment variable MAKEFLAGS="V=1"[1]
implemented in GNU make. However, I wanted to make a consistent user-interface
not depending on the specific make's implementation.

$ ruby /path/to/extconf.rb -- --with-verbose 

You can also add the extra option via rake-compiler gem.

$ rake compiler -- --with-verbose 

If the extra option is not given, the value of the
RbConfig::CONFIG["MKMF_VERBOSE"] enabled by the configure option below is
used.

$ ./configure --enable-mkmf-verbose 

For the unit tests, updated the following files.

• The test/mkmf/test_configuration.rb was created to test the cases with the
  configuration method and this implementation.
• Updated the TestMkmf#assert_separately to set the extra
  arguments in test/mkmf/base.rb. Updated tests using the assert_separately.
• Added tests for MakeMakefile#with_config in the test/mkmf/test_config.rb.

[1] https://www.gnu.org/software/make/manual/html_node/Variables_002fRecursion.html

Fixes [Bug #19695]

Co-authored-by: Nobuyoshi Nakada nobu@ruby-lang.org