cmd/pref: disable -usecache on windows & enable by default (commented)

cmd/v/v.v

@@ -72,6 +72,10 @@ fn main() {
 		// println('prefs= ')
 		// println(prefs) // QTODO
 	}
+	if prefs.use_cache && os.user_os() == 'windows' {
+		eprintln('-usecache is currently disabled on windows')
+		exit(1)
+	}
 	if command == 'test-vet' {
 		println('Please use `v test-cleancode` instead.')
 		return

vlib/v/pref/default.v

@@ -93,6 +93,9 @@ pub fn (mut p Preferences) fill_with_defaults() {
 		'$p.lookup_path',
 	])
 	// eprintln('prefs.cache_manager: $p')
+	//
+	// enable use_cache by default
+	// p.use_cache = os.user_os() != 'windows'
 }
 
 fn (mut p Preferences) try_to_use_tcc_by_default() {