Merge pull request emscripten-core#2256 from juj/more_musl

More musl.

add a Nested branch type in relooper, to represent a path we must mak…

…e sure is nested so that parallel paths do not get intertwined. this allows us to emit a more canonical form of nested ifs as a result of short-circuit operators; 1.13.2

release 1.13.0

Merge pull request emscripten-core#2165 from juj/fs_element_size

Fullscreen element sizes