Bump version to 1.38.27 after updating struct_info.json

Update version to 1.38.26 to enable externUses tracking in fastcomp

Micro-optimize access to emscripten_memcpy_big: moving return stateme…

…nt to wasm side saves 6 bytes (reduces JS code by 9 bytes, increases wasm code by only 3 bytes)

Move legacy GL emulation into its own file library_glemu.js. Restore …

…glDrawArrays() and glDrawElements() to be closure minified.

Implement Musl's atomic primitives for wasm backend (emscripten-core#…

…7594)

Use clang's C11 atomic builtins instead of the emscripten-specific functions.
Keep the emscripten versions, but just use them for fastcomp.