[analyzer] Rename test: cxx17-mandatory-elision.cpp -> copy-elision.cpp

It reflects its contents more accurately. No functional change intended.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@338339 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/test/Analysis/cxx17-mandatory-elision.cpp b/test/Analysis/copy-elision.cpp
similarity index 100%
rename from test/Analysis/cxx17-mandatory-elision.cpp
rename to test/Analysis/copy-elision.cpp