meson: Update rust/meson.build

Targeted build is now available for libraries too.

rust/meson.build

@@ -1,20 +1,27 @@
 cargo_cmd = [cargo, 'build', '--manifest-path=@INPUT@', '--target-dir=@OUTDIR@',
              cargo_build_args]
 
-# the target to compile all rust binaries
-custom_target('rust_binaries',
+rust_libs = ['scx_utils', 'scx_stats', 'scx_rustland_core']
+rust_bins = ['scx_loader']
+
+cargo_bins_args = []
+
+foreach bin : rust_bins
+  cargo_bins_args += ['-p', bin]
+endforeach
+
+# the default target to compile all rust binaries (but no libraries)
+custom_target('rust_bins',
               output: '@PLAINNAME@.__PHONY__',
               input: 'Cargo.toml',
-              command: cargo_cmd,
+              command: cargo_cmd + cargo_bins_args,
               env: cargo_env,
               depends: sched_deps,
               build_by_default: true,
               build_always_stale: true)
 
-# the target to compile loader binary
-rust_binaries = ['scx_loader']
-
-foreach binary: rust_binaries
+# the target to compile individual packages
+foreach binary: rust_libs + rust_bins
   custom_target(binary,
                 output: binary + '@PLAINNAME@.__PHONY__',
                 input: 'Cargo.toml',