update makefile for mingw gcc builds

[chcg]

, see also #3918

Last update was #2478.

[GitMensch]

@chcg Can you please (maybe with an additional PR) adjust https://github.com/notepad-plus-plus/notepad-plus-plus/blob/master/appveyor.yml to include a MinGW GCC build?
If it is integrated there wouldn't be another incompatible change in the future...

[chcg]

@GitMensch See #2478 with just this changes the build still fails, due to ATL, which is not available for mingw. So adding an additional build for it just makes sense, if it is planned to get this build running, either by disabling the problematic code via #ifdef or by some stub similar to #1663. Maybe in the meantime also some new issues were introduced.

Therefore some agreement from donho is needed what will be accepted.

[chcg]

@GitMensch See also #4776 for a probably functional version.

[donho]

@chcg Does this PR still be updated (compiled by MinGW) ?

[chcg]

As this is 2 years old a rebase and adaption to current changes is necessary, reflecting:

• Revision: 581aff6
  Use standard C++11 mutex
  And remove unecessary files
  Close Use standard C++11 mutex #6093
• Revision: 519fecb
  Add SHA-256 implementation and use sha-256 instead of md5 in Plugin Admin

as far as I see. Some commits in the meantime are already helping to get closer to goal to have a mingw build like removal of the ATL by usage of C++11 mutex and Force cpp standard const char pointer on string literals

I could do a rebase and adapt.

[chcg]

So this is WIP, appveyor will be incompatible modified until the makefile is updated.

[chcg]

@donho See https://ci.appveyor.com/project/chcg/notepad-plus-plus/builds/28608301/job/85t95ficdgio8i5h/artifacts, seems to be a first working version, if combined with a signed SciLexer.dll. Quite huge as it is a debug build with all dependency libs apart from SciLexer.dll linked in.

[GitMensch]

This is very good news. Can you target for a non-static non-debug build [a different make target] next?

[donho]

@chcg
Looks good to me.
Sorry for the wait.

[chcg]

@donho
Some points remain I think:

• UserDefineDialog.cpp
  I think it should be possible to do the std::find() also for mingw
• functionListPanel.cpp
  check ofstream usage, maybe via basic_ofstream<TCHAR>
• appveyor.yml mingw config
  scintilla is build just as release version
  notepad++ seems to be just debug

I will work on that for an updated PR and maybe also add a linux build.