PR testsuite/85483: Move aarch64/sve/vcond_1.c test to g++.dg/other/
I totally botched up this sve test file in 259437.
It needs C++, so move it to g++.dg/other and make it a .C file.
Also adds the target guards to prevent it from running on non-aarch64 targets.
Tested that it passes on aarch64-none-elf and doesn't get run on arm-none-eabi.