[wasm][build] Exclude Tools from build when BUILD_TOOLS is OFF

This is a follow up to 5e7281b, which
just adds the `BUILD_TOOLS` option but doesn't actually use it. This
patch renames the option to follow the CMake conventions and uses it to
actually exclude the tools from the build.

Author: kateinoigakukun

CMakeLists.txt

@@ -40,7 +40,7 @@ set(CMAKE_Swift_MODULE_DIRECTORY ${CMAKE_BINARY_DIR}/swift)
 option(BUILD_SHARED_LIBS "build shared libraries" ON)
 option(HAS_LIBDISPATCH_API "has libdispatch API" ON)
 option(BUILD_NETWORKING "build FoundationNetworking module" ON)
-option(BUILD_TOOLS "build tools" ON)
+option(FOUNDATION_BUILD_TOOLS "build tools" ON)
 option(NS_CURL_ASSUME_FEATURES_MISSING "Assume that optional libcurl features are missing rather than test the library's version, for build debugging" NO)
 
 if(HAS_LIBDISPATCH_API)

Sources/CMakeLists.txt

@@ -2,4 +2,6 @@ add_subdirectory(UUID)
 add_subdirectory(Foundation)
 add_subdirectory(FoundationNetworking)
 add_subdirectory(FoundationXML)
-add_subdirectory(Tools)
+if(FOUNDATION_BUILD_TOOLS)
+  add_subdirectory(Tools)
+endif()