Framework search path response file references quoted

Framework search paths consolidated into response files in Derived/FrameworkSearchPaths are now referenced through a quoted “@” token in OTHER_CFLAGS and OTHER_LDFLAGS instead of an unquoted @. Targets whose names include whitespace no longer split the response file reference into multiple arguments, so clang and the linker actually load the consolidated file. Targets without whitespace keep the same response-file behaviour.