parser,util: improve libleak false positive detection rate

vlib/v/parser/module.v

@@ -18,7 +18,7 @@ fn (p &Parser) prepend_mod(name string) string {
 	if p.builtin_mod {
 		return name
 	}
-	return '${p.mod}.$name'
+	return p.mod + '.' + name
 }
 
 fn (p &Parser) is_used_import(alias string) bool {

vlib/v/parser/parser.v

@@ -419,7 +419,7 @@ pub fn (mut p Parser) parse_block() []ast.Stmt {
 
 pub fn (mut p Parser) parse_block_no_scope(is_top_level bool) []ast.Stmt {
 	p.check(.lcbr)
-	mut stmts := []ast.Stmt{}
+	mut stmts := []ast.Stmt{cap: 20}
 	if p.tok.kind != .rcbr {
 		mut count := 0
 		for p.tok.kind !in [.eof, .rcbr] {

vlib/v/util/timers.v

@@ -18,6 +18,7 @@ pub fn new_timers(should_print bool) &Timers {
 	return &Timers{
 		swatches: map[string]time.StopWatch{}
 		should_print: should_print
+		already_shown: []string{cap: 100}
 	}
 }