player: add Emscripten compiler identification
player: add Emscripten compiler identification

Since there is now a working Emscripten support, this commit add the
Emscripten compiler identification, for future debugging.

Signed-off-by: Julien Olivain <e017b3aecfdd2dc1bdcf241eeb088a15ff1e3ada@free.fr>

jolivain/glslsandbox-player,jolivain/glslsandbox-player,jolivain/glslsandbox-player,jolivain/glslsandbox-player