Remove date from test case file name. The PR number provides a unique ID already.

llvm-svn: 176796

diff --git a/llvm/test/CodeGen/ARM/2013-03-09-PR15053.ll b/llvm/test/CodeGen/ARM/PR15053.ll
similarity index 100%
rename from llvm/test/CodeGen/ARM/2013-03-09-PR15053.ll
rename to llvm/test/CodeGen/ARM/PR15053.ll