Add include_dirs to all libraries

One can link directly to `rust_library` as well.

The current logic is brittle: not all crates explicitly list
crate-types, especially because not all crate types are available on all
platforms: e.g. specifying a crate-type staticlib or cdylib makes it
*impossible* to compile a crate to Wasm. On the other hand, crate
consumers are free to specify whatever crate type they'd like via cargo,
so not explicitly listing crate-types is a decent choice for crates.

So the current logic leaves out crates like `icu_capi`, which have
headers but don't have a `staticlib` crate-type.

Test: m cargo_embargo + crate_tool regenerate icu_capi

Change-Id: Iaf62f6abdcc5cd84090f37b1ddc200c9d64e8500

Author: Manishearth

tools/cargo_embargo/src/cargo.rs

@@ -64,11 +64,6 @@ impl CrateType {
     pub fn is_test(self) -> bool {
         matches!(self, Self::Test | Self::TestNoHarness)
     }
-
-    /// Returns whether the crate type is a kind of C ABI library.
-    pub fn is_c_library(self) -> bool {
-        matches!(self, Self::CDyLib | Self::StaticLib)
-    }
 }
 
 /// Info extracted from `CargoOut` for a crate.

tools/cargo_embargo/src/main.rs

@@ -1114,7 +1114,7 @@ fn crate_to_bp_modules(
         if !crate_type.is_test() && package_cfg.host_supported && package_cfg.host_first_multilib {
             m.props.set("compile_multilib", "first");
         }
-        if crate_type.is_c_library() {
+        if crate_type.is_library() {
             m.props.set_if_nonempty("include_dirs", package_cfg.exported_c_header_dir.clone());
         }