Use "MSYS Makefiles" target when buildin on Windows

[PierreTechoueyres]

Avoid using Visual Studio generator when building on Windows system.
(Fix issue #83).

• Makefile: conditionally use MSYS generator.

[tarsius]

Someone familiar with cmake and windows has to review this.

Unlike before CMAKE_CMD_LINE_OPTIONS is now always set to something, not just on msys. Is that intentional? Please explain in the commit message what the two possible values mean and why we have to use them.

[PierreTechoueyres]

Hi @tarsius,
Sorry for the delay. I completely forget this issue.
CMAKE_CMD_LINE_OPTIONS is not an official cmake variable. It's one I defined to avoid the duplication of -DCMAKE_BUILD_TYPE=Debug inside the Makefile.

Could the commit message below be what you expect ?

Avoid using Visual Studio generator when building on Windows system by
using MSYS Makefiles generator on Microsoft Windows systems.

In Microsoft Windows, if Visual Studio is installed, it's the preferred choice of
 cmake before MSYS. But Emacs (and this lib by extension) must be build with
 MSYS. So whe must explicitly say what type of generator cmake should use.

(Fix issue #83).

* Makefile: Conditionally use "MSYS Makefiles generator".  Also
  refactor the definition of build type by defining an
  CMAKE_CMD_LINE_OPTIONS variable.

[PierreTechoueyres]

@tarsius ping ?

[tarsius]

I would still prefer it if @TheBB reviewed this.

Could the commit message below be what you expect ?

Mostly. It also needs to begin with a fairly short oneline summary.

[PierreTechoueyres]

what about:

Avoid using Visual Studio generator when building on Microsoft Windows.

Prrefer using MSYS Makefiles generator over the one provided by 
Microsoft Visual Studio (Fix issue #83).

In Microsoft Windows, if Visual Studio is installed, it's the preferred choice of
 cmake before MSYS. But Emacs (and this lib by extension) must be build with
 MSYS. So whe must explicitly say what type of generator cmake should use.

* Makefile: Conditionally use "MSYS Makefiles generator".  Also
  refactor the definition of build type by defining an
  CMAKE_CMD_LINE_OPTIONS variable.

[tarsius]

I usually don't review commit messages to such an extend, but you asked...

The indentation of the middle paragraph is weird. There are some typos as well; prrefer and whe at least.

Also I don't think you should repeat the same information several times like an American newspaper. In other words drop the last paragraph. Now I realize that I was confused about that variable, so it might make sense to mention it, but the way you are mentioning it right now it doesn't actually do so and so that paragraph doesn't really do much good.

It would be better if you addressed the thing that caused my confusion head on.

CMAKE_CMD_LINE_OPTIONS=-DCMAKE_BUILD_TYPE=Debug

Two variables are mentioned. I am still guessing that CMAKE_BUILD_TYPE is an official variable. If you come to that conclusion, then it is not a stretch to assume that CMAKE_CMD_LINE_OPTIONS is as well. This ambiguity could be addressed by renaming the variable to not use an official sounding name, e.g. BUILD_OPTIONS. (Also why ...CMD_LINE...? That's weird.)

[TheBB]

I'm afraid I'm not really in possession of a Windows build environment other than Appveyor, so I'm happy to let those who actually do build on Windows make the decisions they feel they need.

Since @tarsius left some comments I'll wait until tomorrow to merge/adjust.

[PierreTechoueyres]

I usually don't review commit messages to such an extend, but you asked...

And I really appreciate. I know I'm not very fluent in English, so every help is welcome.

The indentation of the middle paragraph is weird. There are some typos as well; prrefer and whe at least.

Also I don't think you should repeat the same information several times like an American newspaper. In other words drop the last paragraph. Now I realize that I was confused about that variable, so it might make sense to mention it, but the way you are mentioning it right now it doesn't actually do so and so that paragraph doesn't really do much good.

It would be better if you addressed the thing that caused my confusion head on.

CMAKE_CMD_LINE_OPTIONS=-DCMAKE_BUILD_TYPE=Debug

Two variables are mentioned. I am still guessing that CMAKE_BUILD_TYPE is an official variable. If you come to that conclusion, then it is not a stretch to assume that CMAKE_CMD_LINE_OPTIONS is as well. This ambiguity could be addressed by renaming the variable to not use an official sounding name, e.g. BUILD_OPTIONS. (Also why ...CMD_LINE...? That's weird.)

I'll try to provide something tomorrow or on the following days (now it's too late for me. I really should be sleeping from a long time).

[PierreTechoueyres]

@tarsius:
Hope the new version will match what you're expected.