[MIPS64] Add syscall related files

Change-Id: I2f5d05df0e767538a6fe467ca0a2386325f8b71f
Signed-off-by: Chris Dearman <chris.dearman@imgtec.com>
Signed-off-by: Raghu Gandham <raghu.gandham@imgtec.com>
Signed-off-by: Duane Sand <duane.sand@imgtec.com>
diff --git a/libc/arch-mips64/syscalls/sigaltstack.S b/libc/arch-mips64/syscalls/sigaltstack.S
new file mode 100644
index 0000000..3458b11
--- /dev/null
+++ b/libc/arch-mips64/syscalls/sigaltstack.S
@@ -0,0 +1,31 @@
+/* Generated by gensyscalls.py. Do not edit. */
+
+#include <asm/unistd.h>
+#include <machine/asm.h>
+#include <machine/regdef.h>
+    .text
+    .globl sigaltstack
+    .align 4
+    .ent sigaltstack
+
+sigaltstack:
+    .set push
+    .set noreorder
+    li v0, __NR_sigaltstack
+    syscall
+    bnez a3, 1f
+    move a0, v0
+    j ra
+    nop
+1:
+    move t0, ra
+    bal     2f
+    nop
+2:
+    .cpsetup ra, t1, 2b
+    LA t9,__set_errno
+    .cpreturn
+    j t9
+    move ra, t0
+    .set pop
+    .end sigaltstack