build_environment: move llvm/clang to ninja on windows.

build_files/build_environment/cmake/clang.cmake

@@ -23,11 +23,20 @@ set(CLANG_EXTRA_ARGS
 	-DLLVM_USE_CRT_DEBUG=MTd
 	-DLLVM_CONFIG=${LIBDIR}/llvm/bin/llvm-config
 )
+
+if(WIN32)
+	set(CLANG_GENERATOR "Ninja")
+else()
+	set(CLANG_GENERATOR "Unix Makefiles")
+endif()
+
+
 ExternalProject_Add(external_clang
 	URL ${CLANG_URI}
 	DOWNLOAD_DIR ${DOWNLOAD_DIR}
 	URL_HASH MD5=${CLANG_HASH}
 	PREFIX ${BUILD_DIR}/clang
+	CMAKE_GENERATOR ${CLANG_GENERATOR}
 	CMAKE_ARGS -DCMAKE_INSTALL_PREFIX=${LIBDIR}/clang ${DEFAULT_CMAKE_FLAGS} ${CLANG_EXTRA_ARGS}
 	INSTALL_DIR ${LIBDIR}/clang
 )

build_files/build_environment/cmake/llvm.cmake

@@ -26,7 +26,7 @@ set(LLVM_EXTRA_ARGS
 )
 
 if(WIN32)
-	set(LLVM_GENERATOR "NMake Makefiles")
+	set(LLVM_GENERATOR "Ninja")
 else()
 	set(LLVM_GENERATOR "Unix Makefiles")
 endif()