mips: replace addi with addiu

ADDI instruction has been removed in R6 so let's use ADDIU instead.

This patch has been sent upstream:

  https://bugs.kde.org/show_bug.cgi?id=356112

Signed-off-by: Vicente Olivert Riera <Vincent.Riera@imgtec.com>

Index: valgrind/coregrind/m_dispatch/dispatch-mips32-linux.S
===================================================================
--- valgrind/coregrind/m_dispatch/dispatch-mips32-linux.S	(revision 15740)
+++ valgrind/coregrind/m_dispatch/dispatch-mips32-linux.S	(working copy)
@@ -196,7 +196,7 @@
         addu $13, $13, $14
 
         lw $12, 0($13) /* t3 = VG_(tt_fast)[hash] :: ULong* */
-        addi $13, $13, 4
+        addiu $13, $13, 4
         lw $25, 0($13) /* little-endian, so comparing 1st 32bit word */
         nop
 
Index: valgrind/coregrind/m_libcsetjmp.c
===================================================================
--- valgrind/coregrind/m_libcsetjmp.c	(revision 15740)
+++ valgrind/coregrind/m_libcsetjmp.c	(working copy)
@@ -594,7 +594,7 @@
 /* Checking whether second argument is zero. */
 "   bnez $a1, 1f                \n\t"
 "   nop                         \n\t"
-"   addi $a1, $a1, 1            \n\t"  /* We must return 1 if val=0. */
+"   addiu $a1, $a1, 1           \n\t"  /* We must return 1 if val=0. */
 "1:                             \n\t"
 "   move $v0, $a1               \n\t"  /* Return value of second argument. */
 "   j    $ra                    \n\t"
Index: valgrind/coregrind/m_trampoline.S
===================================================================
--- valgrind/coregrind/m_trampoline.S	(revision 15740)
+++ valgrind/coregrind/m_trampoline.S	(working copy)
@@ -1254,8 +1254,8 @@
       //la $a0, string
       j strlen_cond
    strlen_loop:
-      addi $v0, $v0, 1
-      addi $a0, $a0, 1
+      addiu $v0, $v0, 1
+      addiu $a0, $a0, 1
    strlen_cond:
       lbu $t0, ($a0)
       bne $t0, $zero, strlen_loop