ast,build: add Attributes fields to Function and Global

Updates #2

build/context.go

@@ -55,6 +55,10 @@ func (c *Context) Doc(lines ...string) {
 	c.activefunc().Doc = lines
 }
 
+func (c *Context) Attributes(a avo.Attribute) {
+	c.activefunc().Attributes = a
+}
+
 func (c *Context) Signature(s *gotypes.Signature) {
 	c.activefunc().SetSignature(s)
 }

build/global.go

@@ -58,7 +58,8 @@ func ReturnIndex(i int) gotypes.Component  { return ctx.ReturnIndex(i) }
 func Load(src gotypes.Component, dst reg.Register) reg.Register { return ctx.Load(src, dst) }
 func Store(src reg.Register, dst gotypes.Component)             { ctx.Store(src, dst) }
 
-func Doc(lines ...string) { ctx.Doc(lines...) }
+func Doc(lines ...string)        { ctx.Doc(lines...) }
+func Attributes(a avo.Attribute) { ctx.Attributes(a) }
 
 func AllocLocal(size int) operand.Mem { return ctx.AllocLocal(size) }