Use mxcr_mask instead of mxcsr_mask to match glibc.

Bug: 18097559

(cherry picked from commit f485547b9267263e1de220a3cc368deaec367191)

Change-Id: I242105faa8210abc9635a951b25b127cd64ed23c
diff --git a/libc/include/sys/user.h b/libc/include/sys/user.h
index 18684f1..66b371d 100644
--- a/libc/include/sys/user.h
+++ b/libc/include/sys/user.h
@@ -108,7 +108,7 @@
   __u64 rip;
   __u64 rdp;
   __u32 mxcsr;
-  __u32 mxcsr_mask;
+  __u32 mxcr_mask;
   __u32 st_space[32];
   __u32 xmm_space[64];
   __u32 padding[24];