fix: skip importing memfd and rustix crates if std feature is disabled

Signed-off-by: Ho Kim <ho.kim@ulagbulag.io>

Author: HoKim98

crates/fiber/Cargo.toml

@@ -17,8 +17,8 @@ wasmtime-environ = { workspace = true }
 wasmtime-versioned-export-macros = { workspace = true }
 
 [target.'cfg(unix)'.dependencies]
-rustix = { workspace = true, features = ["mm"] }
-libc = { workspace = true }
+rustix = { workspace = true, optional = true, features = ["mm"] }
+libc = { workspace = true, optional = true }
 
 [target.'cfg(windows)'.dependencies.windows-sys]
 workspace = true
@@ -38,4 +38,4 @@ backtrace = "0.3.68"
 
 # Assume presence of the standard library. Allows propagating
 # panic-unwinds across fiber invocations.
-std = []
+std = ["dep:libc", "dep:rustix"]

crates/fiber/src/lib.rs

@@ -7,7 +7,7 @@
 
 #![no_std]
 
-#[cfg(any(feature = "std", unix, windows))]
+#[cfg(feature = "std")]
 #[macro_use]
 extern crate std;
 extern crate alloc;

crates/wasmtime/Cargo.toml

@@ -265,7 +265,6 @@ runtime = [
   "dep:cc",
   "dep:smallvec",
   "dep:mach2",
-  "dep:memfd",
   "dep:wasmtime-versioned-export-macros",
   "dep:windows-sys",
   "pulley-interpreter/interp",
@@ -347,6 +346,7 @@ std = [
   'pulley-interpreter/std',
   'wasmtime-core/std',
   'addr2line?/std',
+  "dep:memfd",
   "dep:rustix",
   "wasmtime-jit-icache-coherence",
   "wasmtime-jit-debug?/std",