I was rebuilding on Termux and noted that mjpegtools and possibly
liba52 now fails to build.

Ah, I thought it was due to clang update, but apparently autoconf can
cause  this, when paired with c23 defaulting compiler

https://www.mail-archive.com/info-gnu@gnu.org/msg03513.html

===

AC_PROG_CC now prefers C23 if available.
  Older code may need to be updated, as C23 has removed old-style
  (K&R) function definitions and declarations, now uses type-generic
  functions for strchr and similar functions, and has new keywords
  alignas, alignof, bool, constexpr, false, nullptr, static_assert,
  thread_local, true, typeof, typeof_unqual.

====

I'll try to prepare patch  as my tablet charge back (after just less
than 4 years of use it hardly compiles half of full cingg build ....
even if plugged in!)

not for this month's release, we already hit enough surprises for
last-minute build changes like this.