LL physics extensions stub

Since the CMakeLists.txt includes some same .cmake files as the viewer,
I think the project might as well be a part of the Linden libraries
code. And for now is put under llprimitive (might not be consistent, in
fact the opposite, with they way llplugin relates to slplugin), but I
think this way results the least change, and it still works.

The differences include:
- all files (common llphysicsextensions headers to be included by
  library users and the stub implementation files) are put inside one
  directory, and the CMakeLists.txt is adjusted accordingly;
- modernised CMakeLists.txt, so include_directories are now implied by
  target_link_libraries;
- some file name fix;
- add_library is not explicitly set to STATIC;

1 files changed, 3 insertions, 0 deletions

diff --git a/indra/cmake/LLPhysicsExtensions.cmake b/indra/cmake/LLPhysicsExtensions.cmake
index 36821447c9..b2151dc781 100644
--- a/indra/cmake/LLPhysicsExtensions.cmake
+++ b/indra/cmake/LLPhysicsExtensions.cmake
@@ -26,6 +26,9 @@ if (HAVOK)
 elseif (HAVOK_TPV)
    use_prebuilt_binary(llphysicsextensions_tpv)
    target_link_libraries( llphysicsextensions_impl INTERFACE llphysicsextensions_tpv)
+elseif (NOT (USE_AUTOBUILD_3P OR USE_CONAN))
+   target_link_libraries( llphysicsextensions_impl INTERFACE llphysicsextensionsstub)
+   return ()
 else (HAVOK)
    use_prebuilt_binary(llphysicsextensions_stub)
    set(LLPHYSICSEXTENSIONS_SRC_DIR ${LIBS_PREBUILT_DIR}/llphysicsextensions/stub)