Fix Android define to standard

[Caerind]

ANDROID is the standard define for Android platform. There is still the USE_JNI that is user-defined, so the code won't be enabled for people not want the feature on Android.

[Caerind]

There are also changes that I needed on my side (but on imgui-sfml v2.6.1):

• Commented glPolygonMode in SetupRenderState
• "ifndef-ed" last_polygon_mode in RenderDrawLists
• "ifndef-ed" glPopAttrib the 2 glPolygonMode in RenderDrawLists

(Edit: Maybe that first commented line could be ifdef instead 🤣)

[eXpl0it3r]

ANDROID is the standard define for Android platform. There is still the USE_JNI that is user-defined, so the code won't be enabled for people not want the feature on Android.

Any source to quote that __ANDROID__ is the right define?

There are also changes that I needed on my side (but on imgui-sfml v2.6.1):

* Commented **glPolygonMode** in SetupRenderState

* "ifndef-ed" **last_polygon_mode** in RenderDrawLists

* "ifndef-ed" **glPopAttrib** the 2 **glPolygonMode** in RenderDrawLists

(Edit: Maybe that first commented line could be ifdef instead 🤣)

Is this in any way related to the given PR?

[Caerind]

I think the safest would be this one: https://github.com/SFML/SFML/blob/ca65abe717cc731b5ee309d25c1291508e163795/include/SFML/Config.hpp#L74

(So I updated the PR to use it directly)

For the comments, it's not directly related to the PR. These are fixes that I needed on Android, but I don't know if they are valid. Just mentioning if that can help anyone using imgui-SFML on Android and having similar issues.