Linux and Windows CMake Builds: Change output executable to lowercase

[F0bes]

Description of Changes

bin/PCSX2 is now bin/pcsx2 -- update your scripts!

Rationale behind Changes

Everything in Linux land is lowercase

Suggested Testing Steps

Build PCSX2 and see if it is lowercase

-- I believe I got everything covered for this change? PCSX2-Linux.sh still works

[Mrlinkwii]

Compiles here , works as intended 👍

[qurious-pixel]

I would expect it to fail to run from the desktop file.

Exec=env GDK_BACKEND=x11 MESA_NO_ERROR=1 PCSX2

Should the desktop file name, be lower-case?

[lightningterror]

I prefer uppercase for PCSX2.

[F0bes]

I would expect it to fail to run from the desktop file.

Exec=env GDK_BACKEND=x11 MESA_NO_ERROR=1 PCSX2

Should the desktop file name, be lower-case?

You're right

I prefer uppercase for PCSX2.

Why?

[lightningterror]

Why?

Seems more right since we use the upper case naming mostly everywhere.

edit: nvm, carry on, ref explained.

[refractionpcsx2]

Sure, in the app and website it's fine since it's an acronym, but the filename should be lower case, especially on linux. Windows has always been lower case.

[fantesykikachu]

Windows has always been lower case.

I just noticed that with the new cmake windows builds the executable filename as uppercase, maybe the PR should do lowercase executables everywhere.

[refractionpcsx2]

Maybe it does, but only with CMake, the VS projects still output a lower case file.

[F0bes]

Rebased.