[FFmpeg-cvslog] configure: warn when threading is disabled

[Anton Khirnov]

ffmpeg | branch: master | Anton Khirnov <anton at khirnov.net> | Tue Oct  3 15:32:30 2023 +0200| [f9fdaa2ca92f1d111c5797e202ea48e6c3eb914f] | committer: Anton Khirnov

configure: warn when threading is disabled

Explicitly state what the implications of this are.

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=f9fdaa2ca92f1d111c5797e202ea48e6c3eb914f
---

 configure | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/configure b/configure
index 7afeebebcd..8ab658f730 100755
--- a/configure
+++ b/configure
@@ -7523,6 +7523,12 @@ check_deps $CONFIG_LIST       \
 
 enabled threads && ! enabled pthreads && ! enabled atomics_native && die "non pthread threading without atomics not supported, try adding --enable-pthreads or --cpu=i486 or higher if you are on x86"
 
+enabled threads || warn \
+    "Threading support was disabled or is not available on the target platform." \
+    "This means that not only is this build not multi-threaded, but also"    \
+    "that the libraries from this build MUST NOT be used in a multi-threaded"\
+    "environment."
+
 case $target_os in
 haiku)
     disable memalign