Add libsolv_rs (#243)

* Enhance create command with additional flags
* Expose experimental libsolv_rs in create command
* Test libsolv_rs in rattler_solve
* Extract libsolv-sys
* Use feature flags for solver backends

.github/workflows/rust-compile.yml

@@ -14,7 +14,7 @@ env:
   RUST_BACKTRACE: 1
   RUSTFLAGS: "-D warnings"
   CARGO_TERM_COLOR: always
-  DEFAULT_FEATURES: tokio,serde,reqwest,sparse,sysinfo
+  DEFAULT_FEATURES: tokio,serde,reqwest,sparse,sysinfo,libsolv-rs
 
 jobs:
   check:

.gitmodules

@@ -1,3 +1,3 @@
 [submodule "crates/rattler/libsolv"]
-	path = crates/rattler_solve/libsolv
+	path = crates/libsolv-sys/libsolv
 	url = https://github.com/baszalmstra/libsolv

crates/libsolv-sys/Cargo.toml

@@ -0,0 +1,25 @@
+[package]
+name = "libsolv-sys"
+version = "0.1.0"
+edition = "2021"
+authors = ["Bas Zalmstra <zalmstra.bas@gmail.com>"]
+description = "Bindings for libsolv"
+categories.workspace = true
+homepage.workspace = true
+repository.workspace = true
+license.workspace = true
+readme.workspace = true
+
+[dependencies]
+libc = { version = "0.2" }
+libz-sys = { version = "1.1.9", default-features = false, features = ["static"] }
+cfg-if = "1.0.0"
+
+[build-dependencies]
+anyhow = "1.0.71"
+cc = "1.0.79"
+cmake = "0.1.50"
+
+[package.metadata.cargo-udeps.ignore]
+# libz-sys is required to build libsolv properly
+normal = ["libz-sys"]