Set USE_STD_C99=0 for libsparse in order to avoid build failure

[RedL0tus]

Otherwise it will throw an error while compiling, not just for Android >= 8

Build log for a failed build: http://termbin.com/6i3r

Huge thanks to @zhxt

[krnlyng]

Is this required for all adaptations? Android 4 - 7/8?

[RedL0tus]

@krnlyng
Well... I'm not sure, but at leaset it's required for Android 7.
The problem is libsparse uses a GNU99 style typeof in its min macro, and it will cause it fail to compile if the compiler use standard C99.
https://github.com/mer-hybris/android_system_core/blob/hybris-10.1/libsparse/output_file.c#L59
And the min macro is the same from CM10.1 to 15.1.

The solution is to set USE_STD_C99=0 or rewrite that macro. I saw someone said he rewrote that macro but he didn't pushed it to anywhere, so...

[krnlyng]

@RedL0tus well currently the USE_STD_C99 was used for android < 8. But the patch you made still has the same detection for USE_STD_C99 and it then unconditionally overwrites it which is a bit weird.
I think the problem is that we had to switch the compiler to g++ for android 8.
In my opinion the best thing is to either, get rid of the whole USE_STD_C99 code, or if that is not possible (due to android code?) then when USE_STD_C99 is set, also use gcc instead of g++.

[RedL0tus]

@krnlyng Oh... I'm afraid that I cannot help on that since I'm not familiar with C/C++. I will close this PR and open an issue instead (since it is still a problem that will cause build failure).