only indirect once

Reference: /n/atom/patch/applied/uarttidy
Date: Thu Jun  5 14:17:01 CES 2014
Signed-off-by: quanstro@quanstro.net

--- /sys/src/9/port/devuart.c	Thu Jun  5 14:16:57 2014
+++ /sys/src/9/port/devuart.c	Thu Jun  5 14:16:58 2014
@@ -833,36 +833,36 @@
 int
 uartgetc(void)
 {
-	Uart *u;
+	int (*getc)(Uart*);
 
-	if((u = consuart) == nil || u->phys->getc == nil)
+	if(consuart == nil || (getc = consuart->phys->getc) == nil)
 		return -1;
-	return u->phys->getc(u);
+	return getc(consuart);
 }
 
 void
 uartputc(int c)
 {
-	Uart *u;
+	void (*putc)(Uart*, int);
 
-	if((u = consuart) == nil || u->phys->getc == nil)
+	if(consuart == nil || (putc = consuart->phys->putc) == nil)
 		return;
-	u->phys->putc(u, c);
+	putc(consuart, c);
 }
 
 void
 uartputs(char *s, int n)
 {
 	char *e;
-	Uart *u;
+	void (*putc)(Uart*, int);
 
-	if((u = consuart) == nil || u->phys->getc == nil)
+	if(consuart == nil || (putc = consuart->phys->putc) == nil)
 		return;
 
 	e = s+n;
 	for(; s<e; s++){
 		if(*s == '\n')
-			u->phys->putc(u, '\r');
-		u->phys->putc(u, *s);
+			putc(consuart, '\r');
+		putc(consuart, *s);
 	}
 }