[*] basic in-house cpp linting (#4039)

- add `#pragma once` to remainder files
- "correcter" defines (ANDROID), see https://groups.google.com/g/android-ndk/c/cf9_f1SLXls
- extra miscelly fixups

Signed-off-by: lizzie <lizzie@eden-emu.dev>

Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/4039
Reviewed-by: MaranBr <maranbr@eden-emu.dev>
Reviewed-by: crueter <crueter@eden-emu.dev>

src/frontend_common/config.cpp

@@ -1009,7 +1009,7 @@ std::string Config::AdjustOutputString(const std::string& string) {
 
     // Windows requires that two forward slashes are used at the start of a path for unmapped
     // network drives so we have to watch for that here
-#ifndef ANDROID
+#ifndef __ANDROID__
     if (string.substr(0, 2) == "//") {
         boost::replace_all(adjusted_string, "//", "/");
         adjusted_string.insert(0, "/");