It's a bit off-topic, but is there a reason to still use the original MinGW and not MinGW-w64? The list only mentions the original one.
I also didn't know that GNU refers to the MIT license as Expat license.
The list also links to several PDF versions of books that are still sold and also not published under a free license. Just mentioning them should be fine. We all know how to use an online search engine if we want to get a copy, don't we?
There also some tools I think should be added: I'm not sure if linking to AddressSanitizer is okay (as its (an underused) part of Clang and GCC), but I consider include-what-you-use, unifdef, and maybe C++ Compiler Explorer a worthwhile addition.
What about mbedTLS (formerly PolarSSL)? It's dual licensed though.
Edit: midipix is something one should look out for. What it promises to support and how, sounds much more appealing to me than Cygwin or MinGW-w64, but it's still in early development: http://midipix.org/
I also didn't know that GNU refers to the MIT license as Expat license.
The list also links to several PDF versions of books that are still sold and also not published under a free license. Just mentioning them should be fine. We all know how to use an online search engine if we want to get a copy, don't we?