sync mips libc bits. need to tackle locking.

Reference: /n/atom/patch/applied/mipslibcsync
Date: Tue Apr 15 23:24:54 CES 2014
Signed-off-by: quanstro@quanstro.net

--- /sys/src/libc/mips/tas.s	Tue Apr 15 23:24:54 2014
+++ /sys/src/libc/mips/tas.s	Tue Apr 15 23:24:54 2014
@@ -17,6 +17,7 @@
 	BLTZ	R1, btas
 	RET
 
+	TEXT	_tas(SB), $0
 	TEXT	C_4ktas(SB), $0
 	MOVW	R1, R2		/* address of key */
 tas1:
--- /sys/src/libc/mips/atom.s	Tue Apr 15 23:24:54 2014
+++ /sys/src/libc/mips/atom.s	Tue Apr 15 23:24:54 2014
@@ -6,26 +6,27 @@
 #define	SC(base, rt)	WORD	$((070<<26)|((base)<<21)|((rt)<<16))
 #define	NOOP		WORD	$0x27
 
-TEXT ainc(SB), 1, $-4			/* int ainc(int *); */
+TEXT ainc(SB), 1, $-4			/* long ainc(long *); */
 TEXT _xinc(SB), 1, $-4			/* void _xinc(long *); */
 	MOVW	R1, R2			/* address of counter */
 loop:	MOVW	$1, R3
 	LL(2, 1)
 	NOOP
-	ADD	R1,R3,R3
+	ADDU	R1, R3
+	MOVW	R3, R1			/* return new value */
 	SC(2, 3)
 	NOOP
 	BEQ	R3,loop
 	RET
 
-TEXT adec(SB), 1, $-4			/* int adec(int*); */
+TEXT adec(SB), 1, $-4			/* long adec(long*); */
 TEXT _xdec(SB), 1, $-4			/* long _xdec(long *); */
 	MOVW	R1, R2			/* address of counter */
 loop1:	MOVW	$-1, R3
 	LL(2, 1)
 	NOOP
-	ADD	R1,R3,R3
-	MOVW	R3, R1
+	ADDU	R1, R3
+	MOVW	R3, R1			/* return new value */
 	SC(2, 3)
 	NOOP
 	BEQ	R3,loop1