w32: Make the extra check for a compliant RNG actually work.

* common/compliance.c (gnupg_rng_is_compliant) [W32]: Fix setting
non-compliance.

which introduced a per mode cache but missed to actually reset the
variable on a non-compliant RNG as told by Libgcrypt. This is
intended as an extra security check in case a modified Libgcrypt with
a version >= 1.8.1 and < 1.9.0 is used.

• Fixes-commit: 8ef0f53cb0014026d0d58b8de2133310d96bc1e3