[NFC] Test is C++, not C

llvm-svn: 357524

diff --git a/compiler-rt/test/tsan/libdispatch/groups-destructor.c b/compiler-rt/test/tsan/libdispatch/groups-destructor.cc
similarity index 100%
rename from compiler-rt/test/tsan/libdispatch/groups-destructor.c
rename to compiler-rt/test/tsan/libdispatch/groups-destructor.cc