[build] Fix s390x compile errors

[tasleson]

see: tokio-rs/io-uring#333

resolves: #43

[tasleson]

Ugh: I was getting this to compile on s390x, now it's not, hold off on merging.

[tasleson]

This works if I do something like this on s390x:

io-uring = { version = "^0.7", features = ["bindgen"]  }

But not on x86, and this doesn't work for s390x, but it does for x86

diff --git a/Cargo.toml b/Cargo.toml
index e613a62..f528df2 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -35,7 +35,15 @@ anyhow = "1.0.66"
 
 [dependencies]
 libc = "0.2"
-io-uring = {version="=0.7.9"}
+
+
+[target.'cfg(target_arch = "s390x")'.dependencies]
+io-uring = { version = "=0.7.9", features = ["bindgen"] }
+
+[target.'cfg(not(target_arch = "s390x"))'.dependencies]
+io-uring = { version = "=0.7.9" }
+
+

As I'm using rust2rpm for packaging this needs to be self contained within the cargo build to keep this easier.

[tasleson]

Ok this is working now, I had to learn something new the hard way, ugh

[ming1]

BTW, just be curious, the s390x build failure isn't triggered on Fedora rublk build:

https://koschei.fedoraproject.org/package/rust-rublk?collection=f44