testsuite: Rename a test

I mistyped the file name :(.

gcc/testsuite/ChangeLog:

	PR target/120807
	* gcc.c-torture/compile/pr120708.c: Rename to ...
	* gcc.c-torture/compile/pr120807.c: ... here.

diff --git a/gcc/testsuite/gcc.c-torture/compile/pr120708.c b/gcc/testsuite/gcc.c-torture/compile/pr120807.c
similarity index 100%
rename from gcc/testsuite/gcc.c-torture/compile/pr120708.c
rename to gcc/testsuite/gcc.c-torture/compile/pr120807.c