Compile qdoc in Qt 5.11 with MinGW

From Qqt 5.11, qdoc depends on libclang.
https://bugreports.qt.io/browse/QTBUG-66353
Qt Creator is also said to use clang codemodel as their main C++ parser instead of their homemade one, and now qdoc follows.

OK. Good. Understandable..... But, we have a problem - libclang is not build with MinGW 5.3. LLVM buildbot claims that they use GCC 5.3, internally they seem to use MinGW 7.1. It looks like Qt will upgrade their MinGW to 7.3 from Qt 5.12(7.1 looks buggy so they have to use 7.3 instead).
https://bugreports.qt.io/browse/QTBUG-66015?focusedCommentId=402146&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#comment-402146
So, now we have the core reason and solution. But in Qt 5.11, due to lack of time thanks to that target release date, in 5.11 Qt still uses MinGW 5.3 but they blocked building qdoc. And Qt 5.12, which is expected to solve the issue, will be released some time around Nov.29th. Yep. MinGW users should endure the pain of not-accessible-at-all to the documentation, which is one of the selling point for Qt(you can use online docs, but it's still unconvenient).

But, who are we? We're developers. And Qt is open source project. We can itch wherever is itching. So, I built qdoc with MinGW.

Prerequisites are as follows:

1. Source code of Qt
2. MinGW-w64: 7.3 or higher
3. LLVM library prebuilt by Qt: it's a bit hard to find....... But here you go:
   http://download.qt.io/development_releases/prebuilt/libclang/

If you're going to build Qt Creator too, choose libclang-release_50-windows-mingw series(as of current clang codemodel supports only libclang 5.0).

To build qdoc by yourself, unzip Qt source code and libclang, and change the project file of qdoc. The location is as follows:
QtSourceCode/qttools/src/qdoc/qdoc.pro

Put the following two lines into the top of the project file:

• INCLUDEPATH+=/Qt_prebuilt_clang/unzipped/include
• LIBS+=-L/Qt_prebuilt_clang/unzipped/lib -llibclang.dll

After that, build Qt as usual using configure and mingw32-make, and manually build qdoc.pro.

It would be great if there's someone who experienced inconveniences due to lack of documentation with MinGW, but is relieved with this.