testsuite: g++.dg: fix PR90313 filename

gcc/testsuite/ChangeLog:
	PR c++/90313

	* g++.dg/torture/pr90313.cc: Move to...
	* g++.dg/torture/pr90313.C: ...here.

diff --git a/gcc/testsuite/g++.dg/torture/pr90313.cc b/gcc/testsuite/g++.dg/torture/pr90313.C
similarity index 100%
rename from gcc/testsuite/g++.dg/torture/pr90313.cc
rename to gcc/testsuite/g++.dg/torture/pr90313.C