`include!` uses the wrong search path when it is inside an `asm!` macro invocation

For example, `include_str!` invocation [here](https://github.com/QuiltOS/libfringe/blob/6f30dc8e12025ad2ab426bc82d8974619143dd24/src/arch/x86/mod.rs#L8) in [this expansion](https://github.com/QuiltOS/libfringe/blob/6f30dc8e12025ad2ab426bc82d8974619143dd24/src/arch/x86_common.rs#L24) should search in `src/arch` but instead searches in `src/arch/x86`.
