internal/rosa: respect preferred loadavg target

This generally improves build performance and system responsiveness.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/rosa/cmake.go

@@ -61,10 +61,10 @@ func (attr *CMakeHelper) script(t Toolchain, name string) string {
 	}
 
 	generate := "Ninja"
-	test := "ninja " + jobsFlagE + " test"
+	test := "ninja " + jobsFlagE + " " + loadFlagE + " test"
 	if attr.Make {
 		generate = "'Unix Makefiles'"
-		test = "make " + jobsFlagE + " test"
+		test = "make " + jobsFlagE + " " + loadFlagE + " test"
 	}
 	if attr.Test != "" {
 		test = attr.Test
@@ -97,7 +97,7 @@ cmake -G ` + generate + ` \
 	}), " \\\n\t") + ` \
 	-DCMAKE_INSTALL_PREFIX=/system \
 	'/usr/src/` + name + `/` + filepath.Join(attr.Append...) + `'
-cmake --build . --parallel=` + jobsE + `
+cmake --build . --parallel=` + jobsE + ` -- ` + loadFlagE + `
 DESTDIR=/work cmake --install .
 ` + script
 }