Restore integration and doctest support in CI

This commit adds an unstable `ci` feature which reverts back the
previous non-compliant opening method because it enables tests to run in
CI without needing to painstakingly extract the test binary names from
`cargo build --tests --message-format json` and spawn each one in
`renderdoccmd capture $NAME`. Besides, this strategy is impossible
anyway because doctests compiled on-the-fly by `rustdoc` and do not have
external binaries with which to launch with RenderDoc. We also cannot
make the `RTLD_NOLOAD` conditional, i.e. `#[cfg(any(test, doctest))]`
and `#[cfg(not(any(test, doctest)))]`, due to:

rust-lang/rust#67295

As such, this internal crate feature will have to do.

Cargo.toml

@@ -19,6 +19,12 @@ all-features = true
 [badges]
 circle-ci = { repository = "ebkalderon/renderdoc-rs" }
 
+[features]
+default = []
+
+# Private feature only intended for doctests in CI
+ci = []
+
 [dependencies]
 bitflags = "1.0"
 float-cmp = "0.9"

src/version.rs

@@ -61,6 +61,7 @@ pub trait Version {
         let lib_path = "libVkLayer_GLES_RenderDoc.so";
 
         unsafe {
+            #[cfg(not(feature = "ci"))]
             #[cfg(unix)]
             let lib = LIBRARY
                 .get_or_try_init(|| {
@@ -72,13 +73,19 @@ pub trait Version {
                 })
                 .map_err(Error::library)?;
 
+            #[cfg(not(feature = "ci"))]
             #[cfg(windows)]
             let lib = LIBRARY
                 .get_or_try_init(|| {
                     libloading::os::windows::Library::open_already_loaded(lib_path).map(Into::into)
                 })
                 .map_err(Error::library)?;
 
+            #[cfg(feature = "ci")]
+            let lib = LIBRARY
+                .get_or_try_init(|| Library::new(lib_path))
+                .map_err(Error::library)?;
+
             let get_api: Symbol<GetApiFn> =
                 lib.get(b"RENDERDOC_GetAPI\0").map_err(Error::symbol)?;