[AVR] Mark a failing symbolizer test as XFAIL

llvm-svn: 309512
diff --git a/llvm/test/tools/llvm-symbolizer/print_context.c b/llvm/test/tools/llvm-symbolizer/print_context.c
index 3fd881c..5d0b298 100644
--- a/llvm/test/tools/llvm-symbolizer/print_context.c
+++ b/llvm/test/tools/llvm-symbolizer/print_context.c
@@ -1,6 +1,9 @@
 // REQUIRES: x86_64-linux
 // RUN: %host_cc -O0 -g %s -o %t 2>&1
 // RUN: %t 2>&1 | llvm-symbolizer -print-source-context-lines=5 -obj=%t | FileCheck %s
+//
+// See PR31870 for more details on the XFAIL
+// XFAIL: avr
 
 #include <stdio.h>