MIPS: Convert __syscall_error() callers to use $a0 for argument

Some callers passed the first argument in $v0, while others used $a0.
Change the callers to use $a0 consistently.

Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>

libc/sysdeps/linux/mips/vfork.S

@@ -84,6 +84,7 @@ NESTED(__vfork,FRAMESZ,sp)
 
 	/* Something bad happened -- no child created.  */
 L(error):
+	move	a0, v0
 #ifdef __PIC__
 	PTR_LA		t9, __syscall_error
 	RESTORE_GP64

libpthread/linuxthreads/sysdeps/unix/sysv/linux/mips/mips64/sysdep-cancel.h

@@ -31,7 +31,7 @@
 # undef PSEUDO
 # define PSEUDO(name, syscall_name, args)				      \
   .align 2;								      \
-  99:									      \
+  99: move a0, v0; 							      \
   PTR_LA t9,__syscall_error;					 	      \
   /* manual cpreturn.  */						      \
   REG_L gp, STKOFF_GP(sp);						      \

libpthread/linuxthreads/sysdeps/unix/sysv/linux/mips/vfork.S

@@ -80,6 +80,7 @@ NESTED(__vfork,FRAMESZ,sp)
 
 	/* Something bad happened -- no child created.  */
 L(error):
+	move		a0, v0
 #ifdef __PIC__
 	PTR_LA		t9, __syscall_error
 	RESTORE_GP64