Remove `-std=gnu99` when `enable_cxx_abi`; ref
To stop warnings since C++ do not accept `-std=gnu99` option.
MODIFY
lib/mruby/build.rb
lib/mruby/build.rb
@@ -162,8 +162,8 @@ module MRuby
compilers.each { |c|
c.defines += %w(MRB_ENABLE_CXX_EXCEPTION MRB_ENABLE_CXX_ABI)
c.flags << c.cxx_compile_flag
+ c.flags.delete('-std=gnu99')
}
- compilers.each { |c| c.flags << c.cxx_compile_flag }
linker.command = cxx.command if toolchains.find { |v| v == 'gcc' }
@cxx_abi_enabled = true
end

Remove `-std=gnu99` when `enable_cxx_abi`; ref #4703

To stop warnings since C++ do not accept `-std=gnu99` option.