This commit removes the architecture-specific headers, by keeping only the OS-specific ones.
The different headers were needed to keep the legacy Windows header, after we created the "procptr32_t" (4 bytes) and "procptr64_t" (8 bytes) variables.
We created these variables because the "peekProc" functions read as many bytes as the variable can hold. A pointer is 4 bytes on 32 bit platforms and 8 bytes on 64 bit ones.
Now there's a new variable, called "procptr_t" and with a size of 8 bytes (unsigned long long).
We had a "peekProc" template function which returned the value stored at the specified memory address, but it has been used only to read pointers so far.
Since we needed a new function that checks the process architecture and sets the correct size of the memory to read, I decided to "recycle" it.
The idea is that we can use the CONFIG option until we've fixed the
remaining plugins.
Once all plugins have been transitioned over to the new explicit
pointer types, we can drop the mumble_plugin_win32.h header and
point people to mumble_plugin_win32_x86.h and mumble_plugin_win32_x64.h.
