Commit 211cde09 for xz

commit 211cde09236165dbd379644753337be1de64b151
Author: Lasse Collin <lasse.collin@tukaani.org>
Date:   Mon Nov 3 12:41:31 2025 +0200

    mythread.h: Fix the build on Emscripten when threading is disabled

    To make a non-threaded liblzma-only build work with WASI SDK, <signal.h>
    and mythread_sigmask() were omitted from mythread.h in the commit
    81db3b889830. This broke non-threaded full build with Emscripten because
    src/xz/signals.c needs mythread_sigmask() (liblzma-only build was fine).

    If __wasm__ is defined, omit <signal.h> and mythread_sigmask() in
    non-threaded builds only when __EMSCRIPTEN__ isn't defined.

    Reported-by: Marcus Tillmanns
    Thanks-to: ChanTsune
    Fixes: https://github.com/tukaani-project/xz/issues/161
    Fixes: 81db3b889830 ("mythread.h: Disable signal functions in builds targeting Wasm + WASI.")

diff --git a/src/common/mythread.h b/src/common/mythread.h
index 10ea2d42..bec69b44 100644
--- a/src/common/mythread.h
+++ b/src/common/mythread.h
@@ -78,7 +78,8 @@ do { \
 } while (0)


-#if !(defined(_WIN32) && !defined(__CYGWIN__)) && !defined(__wasm__)
+#if !(defined(_WIN32) && !defined(__CYGWIN__)) \
+		&& (!defined(__wasm__) || defined(__EMSCRIPTEN__))
 // Use sigprocmask() to set the signal mask in single-threaded programs.
 #include <signal.h>