chore(profiling): pass python3 root dir from standalone build script (#…

…11025)

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ddtrace/internal/datadog/profiling/build_standalone.sh

@@ -95,6 +95,7 @@ cmake_args=(
  -DCMAKE_EXPORT_COMPILE_COMMANDS=ON
  -DCMAKE_VERBOSE_MAKEFILE=ON
  -DLIB_INSTALL_DIR=$(realpath $MY_DIR)/lib
+ -DPython3_ROOT_DIR=$(python3 -c "import sysconfig; print(sysconfig.get_config_var('prefix'))")
 )
 
 # Initial build targets; no matter what, dd_wrapper is the base dependency, so it's always built