[PATCH 0/1] MR1982: notepad: Fix uninitialized upper 64-bits of `pos` in DoFind.

[Gabriel Ivăncescu (＠insn)]

`EM_GETSEL` fills a `DWORD` only, so using a `SIZE_T` would leave upper bits to contain random values. We could initialize it to 0, but instead, just get rid of all the pointer cast hacks and use a proper pointer to check if it was found or not. In fact, this removes the duplication with setting pos to ~0, too.