Pass CMAKE_TOOLCHAIN_FILE if crosscompiling (#112)

sqlite3_vendor/CMakeLists.txt

@@ -5,12 +5,20 @@ list(INSERT CMAKE_MODULE_PATH 0 "${CMAKE_CURRENT_SOURCE_DIR}/cmake/Modules")
 find_package(SQLite3)
 
 if (NOT SQLite3_FOUND)
+  set(extra_cmake_args)
+
+  if(DEFINED CMAKE_TOOLCHAIN_FILE)
+    list(APPEND extra_cmake_args "-DCMAKE_TOOLCHAIN_FILE=${CMAKE_TOOLCHAIN_FILE}")
+  endif()
+
   include(ExternalProject)
   ExternalProject_Add(sqlite3-3.24.0
     PREFIX sqlite3-3.24.0
     URL https://www.sqlite.org/2018/sqlite-amalgamation-3240000.zip
     URL_MD5 4ea1e0c6e7e82cb0490d4753d6878698
-    CMAKE_ARGS -DCMAKE_INSTALL_PREFIX=${CMAKE_CURRENT_BINARY_DIR}/sqlite3_install
+    CMAKE_ARGS
+      -DCMAKE_INSTALL_PREFIX=${CMAKE_CURRENT_BINARY_DIR}/sqlite3_install
+      ${extra_cmake_args}
     INSTALL_DIR "${CMAKE_CURRENT_BINARY_DIR}/sqlite3_install"
     PATCH_COMMAND
     ${CMAKE_COMMAND} -E copy "${CMAKE_CURRENT_SOURCE_DIR}/sqlite3_cmakelists.txt" <SOURCE_DIR>/CMakeLists.txt
@@ -30,4 +38,4 @@ install(DIRECTORY cmake DESTINATION share/${PROJECT_NAME})
 install(FILES
   "${PROJECT_BINARY_DIR}/sqlite3_vendorConfig.cmake"
   "${PROJECT_BINARY_DIR}/sqlite3_vendorConfig-version.cmake"
-  DESTINATION share/${PROJECT_NAME}/cmake)
+  DESTINATION share/${PROJECT_NAME}/cmake)