Fix build of check-llvm-spirv target after 8f8001a

Author: vmaksimo

llvm-spirv/test/lit.site.cfg.py.in

@@ -15,7 +15,7 @@ config.target_triple = "@TARGET_TRIPLE@"
 config.host_arch = "@HOST_ARCH@"
 config.python_executable = "@PYTHON_EXECUTABLE@"
 config.test_run_dir = "@CMAKE_CURRENT_BINARY_DIR@"
-config.spirv_tools_found = @SPIRV_TOOLS_FOUND@
+config.spirv_tools_found = "@SPIRV_TOOLS_FOUND@"
 config.spirv_tools_have_spirv_as = @SPIRV_TOOLS_SPIRV_AS_FOUND@
 config.spirv_tools_have_spirv_link = @SPIRV_TOOLS_SPIRV_LINK_FOUND@
 config.spirv_tools_have_spirv_val = @SPIRV_TOOLS_SPIRV_VAL_FOUND@