MinGW: Fix regression when windres is not found

The fix in commit e9755bc7c1 (MinGW: Restore using windres when
toolchain-prefixed name is not available, 2022-08-15, v3.24.1~4^2)
incorrectly listed two entries in `CMAKE_RC_COMPILER_INIT`, which is
only meant to have one value.  Revise the logic to support multiple
platform-specific names for the Windows Resource Compiler while still
only using one name as the fallback when it is not found.

Fixes: #24190
Issue: #23841