assimp: Do not treat warnings as errors

ASSIMP_WARNINGS_AS_ERRORS defaults to ON, which builds the library with
-Wall -Werror. That leaves the build at the mercy of whatever a new
compiler adds to -Wall: clang 23 enables -Wunused-template there, and the
bundled openddlparser copy carries a template that is never called, so the
build fails with

  contrib/openddlparser/code/DDLNode.cpp:34:20: error: unused function
  template 'releaseDataType' [-Werror,-Wunused-template]

Neither assimp master nor openddl-parser upstream has removed that dead
template, and there is no pending pull request for it, so there is nothing
to backport. Debian, Fedora, Arch and Alpine all turn this option off
rather than patch individual warnings; do the same, which also keeps the
next addition to -Wall from breaking the build again.

AI-Generated: Uses Claude Code
Signed-off-by: Khem Raj <raj.khem@gmail.com>

meta-oe/recipes-graphics/assimp/assimp_git.bb

@@ -25,6 +25,7 @@ EXTRA_OECMAKE = "\
     -DCMAKE_INSTALL_LIBDIR=${baselib} \
     -DCMAKE_SKIP_RPATH=ON \
     -DCMAKE_BUILD_WITH_INSTALL_RPATH=OFF \
+    -DASSIMP_WARNINGS_AS_ERRORS=OFF \
 "
 
 do_install:append() {