app-misc/watchexec: fix tests invocation for library part

This package is internally consists of library and CLI.
Library part contains a dummy executable which fails to compile, so
fixed to run tests for library without attempting to build everything.

Closes: https://bugs.gentoo.org/789120
Package-Manager: Portage-3.0.20, Repoman-3.0.3
Signed-off-by: YOSHIOKA Takuma <lo48576@hard-wi.red>

app-misc/watchexec/watchexec-1.16.0.ebuild

@@ -132,3 +132,8 @@ src_install() {
 	insinto /usr/share/zsh/site-functions
 	newins completions/zsh _watchexec
 }
+
+src_test() {
+	cargo_src_test --manifest-path lib/Cargo.toml --lib
+	cargo_src_test --manifest-path cli/Cargo.toml
+}

app-misc/watchexec/watchexec-1.16.1.ebuild

@@ -157,3 +157,8 @@ src_install() {
 	insinto /usr/share/zsh/site-functions
 	newins completions/zsh _watchexec
 }
+
+src_test() {
+	cargo_src_test --manifest-path lib/Cargo.toml --lib
+	cargo_src_test --manifest-path cli/Cargo.toml
+}