std.builtin: Remove CallingConvention.arm_(apcs,aapcs16_vfp).

* arm_apcs is the long dead "OABI" which we never had working support for.
* arm_aapcs16_vfp is for arm-watchos-none which is a dead target that we've
  dropped support for.
9c015e6c2bAlex Rønne Petersen committed on 2/17/2025, 6:17:56 PMparent2fe32ef
8 files changedLine totals unavailable