Emscripten now warns against passing e.g. “ALLOW_MEMORY_GROWTH”
as a compile option.
Add EMCC_THREAD_CFLAGS, which gets compiler flags only.
Pick-to: 6.3
Change-Id: Ifcf40c45ca75cfdfc98a12e6b9d47f34158b3407
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>
Reviewed-by: Lorn Potter <lorn.potter@gmail.com>