Build 8850

commit 4129b794f089ed12618358262c28893a1343df37
Merge: 12086fff8 4b3321e99
Author: Richard Gobeille <richard@voidpoint.com>
Date:   Mon Apr 13 15:02:32 2020 -0700

    Merge branch 'Engine_StutterFixes' into 'master'
    
    build/src/sdlayer.cpp: Add new CVARs r_glfinish & r_finishbeforeswap.
    
    See merge request terminx/eduke32!1

commit 4b3321e99653f2bf3a059ad265f541dd709bec44
Author: Richard Gobeille <richard@voidpoint.com>
Date:   Mon Apr 13 15:00:50 2020 -0700

    Update source/build/src/sdlayer.cpp, source/build/src/polymost.cpp, source/build/src/baselayer.cpp, source/build/include/baselayer.h files

commit e15e2efe6a450b0cd23aef19b70067b54c1ee1a1
Author: Mitchell Richters <mjr4077au@gmail.com>
Date:   Mon Apr 13 18:16:55 2020 +1000

    build/src/sdlayer.cpp: Add new CVAR r_glfinish to make 'glFinish()' optional.
    
    - Issues requiring glFinish() aren't really apparent on Linux, therefore not needed.
    - Running glFinish() can have an detrimental impact of Polymer users depending on whether they use the HRP or not.

commit c92fe8f70d1cdbfa84a58ce143e945bed3ea2ae3
Author: Mitchell Richters <mjr4077au@gmail.com>
Date:   Thu Apr 9 22:17:03 2020 +1000

    build/src/sdlayer.cpp: Add new CVAR r_finishbeforeswap.
    
    - glFinish() after swapping stabilises stuttering issues and has minimum performance impact.
    - glFinish() before swapping stabilises should be better but sometimes isn't, and is needed for KMT not to tear. Offer as an option.

See https://voidpoint.io/terminx/eduke32 for more details.