adopt work-around from pinocchio for finding numpy in x-compilation

recipe/build-pkg.sh

@@ -13,18 +13,27 @@ if [[ "${target_platform}" == linux-* ]]; then
     export CXXFLAGS="$CXXFLAGS -DSWIGWORDSIZE64"
 fi
 
-PYTHON_LIB="${PREFIX}/lib/libpython${PY_VER}${SHLIB_EXT}"
-PYTHON_INC="$PREFIX/include/python${PY_VER}"
-NUMPY_INC=$(python -c 'import numpy;print(numpy.get_include())')
+export BUILD_NUMPY_INCLUDE_DIRS=$( $PYTHON -c "import numpy; print (numpy.get_include())")
+export TARGET_NUMPY_INCLUDE_DIRS=$SP_DIR/numpy/core/include
+
+echo $BUILD_NUMPY_INCLUDE_DIRS
+echo $TARGET_NUMPY_INCLUDE_DIRS
+
+export GENERATE_PYTHON_STUBS=1
+if [[ $CONDA_BUILD_CROSS_COMPILATION == 1 ]]; then
+  echo "Copying files from $BUILD_NUMPY_INCLUDE_DIRS to $TARGET_NUMPY_INCLUDE_DIRS"
+  mkdir -p $TARGET_NUMPY_INCLUDE_DIRS
+  cp -r $BUILD_NUMPY_INCLUDE_DIRS/numpy $TARGET_NUMPY_INCLUDE_DIRS
+fi
 
 # Build vanilla version (no avx2), see build-lib.sh
 cmake -G Ninja \
     ${CMAKE_ARGS} \
     -Dfaiss_ROOT=_libfaiss_stage/ \
     -DCMAKE_BUILD_TYPE=Release \
-    -DPython_INCLUDE_DIRS="${PYTHON_INC}" \
-    -DPython_LIBRARIES="${PYTHON_LIB}" \
-    -DPython_NumPy_INCLUDE_DIRS=${NUMPY_INC} \
+    -DPython_INCLUDE_DIRS="$PREFIX/include/python${PY_VER}" \
+    -DPython_LIBRARIES="${PREFIX}/lib/libpython${PY_VER}${SHLIB_EXT}" \
+    -DPython_NumPy_INCLUDE_DIRS=$TARGET_NUMPY_INCLUDE_DIR \
     -B _build_python \
     faiss/python
 cmake --build _build_python --target swigfaiss -j $CPU_COUNT