Build pybindings with -D_GLIBCXX_USE_CXX11_ABI=0 to match libtorch.so

libtorch.so builds with the old glibc ABI, so we need to as well,
for any source files that include torch headers.

Author: dbort

CMakeLists.txt

@@ -528,9 +528,14 @@ if(EXECUTORCH_BUILD_PYBIND)
                PATHS "${TORCH_INSTALL_PREFIX}/lib")
 
   # compile options for pybind
-
-  set(_pybind_compile_options -Wno-deprecated-declarations -fPIC -frtti
-                              -fexceptions)
+  set(_pybind_compile_options
+      -Wno-deprecated-declarations
+      -fPIC
+      -frtti
+      -fexceptions
+      # libtorch is built with the old ABI, so we need to do the same for any
+      # .cpp files that include torch, c10, or ATen targets.
+      -D_GLIBCXX_USE_CXX11_ABI=0)
   # util lib
   add_library(
     util