internal/rosa: respect preferred job count

This discontinues use of nproc, and also overrides detection behaviour in ninja.

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

internal/rosa/cmake.go

@@ -91,7 +91,7 @@ index 2ead810437..f85cbb8b1c 100644
 		ConfigureName: "/usr/src/cmake/bootstrap",
 		Configure: []KV{
 			{"prefix", "/system"},
-			{"parallel", `"$(nproc)"`},
+			{"parallel", jobsE},
 			{"--"},
 			{"-DCMAKE_USE_OPENSSL", "OFF"},
 			{"-DCMake_TEST_NO_NETWORK", "ON"},
@@ -170,10 +170,8 @@ func (attr *CMakeHelper) script(name string) string {
 	}
 
 	generate := "Ninja"
-	jobs := ""
 	if attr.Make {
 		generate = "'Unix Makefiles'"
-		jobs += ` "--parallel=$(nproc)"`
 	}
 
 	return `
@@ -191,7 +189,7 @@ cmake -G ` + generate + ` \
 	}), " \\\n\t") + ` \
 	-DCMAKE_INSTALL_PREFIX=/system \
 	'/usr/src/` + name + `/` + filepath.Join(attr.Append...) + `'
-cmake --build .` + jobs + `
+cmake --build . --parallel=` + jobsE + `
 cmake --install . --prefix=/work/system
 ` + attr.Script
 }