* Install rake compiler
* Add kokoro config to build ruby gem on linux
* Rename from linix to linux
* Fix prepare_build.sh name
* Clean up
* Install bundler
* Install bundler
* Use c99 in order to build gem on mingw-32 on ruby 2.0.0
See https://github.com/rake-compiler/rake-compiler-dock/issues/4
* Move c99 config to extcofig.rb
This configuration builds both 32-bit and 64-bit binaries for Mac OS X.
One thing I had to change was to increase our minimum supported version
for 10.7 to 10.9, because 10.9 (Mavericks) appears to be the earliest
version supporting C++11.
This will allow SourceLink as per #4179, and mean that we can use C#
7.0 language features in the library (but not in generated code).
This does not affect which platforms we're *targeting*, so end users
won't see any difference.
It would be nice to update to 2.1.4, but AppVeyor's "Visual Studio
2017" environment is only 2.0.3.