[CMAKE] Disable PIE when fixing Box64 load address

[VoltrexKeyva]

When Box64 is built with Clang on distributions where PIE is enabled by default, the current CMake configuration can produce a PIE executable even though Box64 is linked with --image-base=0x34800000.

--image-base does not disable PIE with Clang/LLD, so the resulting ET_DYN executable can be relocated to a high address at runtime.

This breaks Box32 because some Box32 data structures must be addressable through 32-bit pointers. For example, wrappedlibc converts the address of its ctype tables with to_ptrv(), which rejects host pointers above 32 bits and aborts.

For reproduction I tested on Debian 13 Arm64 with Clang/LLD:

Both Box64 v0.4.4 branch and latest main branch with
-DARM_DYNAREC=ON -DBOX32=ON -DBOX32_BINFMT=ON -DCMAKE_BUILD_TYPE=RelWithDebInfo

and the resulting executable is Type: DYN (Shared object file) with a preferred load address of 0x34800000, but is relocated to a high 0xaaaa... address at runtime. Box32 then aborts during wrappedlibc_init32():

[BOX32] Warning, pointer 0xaaaa... is not a 32bits value

The failure was localized with LLDB to:

box64_abort
-> to_ptrv()
-> ctSetup()
-> wrappedlibc_init32()

---

Adding -no-pie to the link flags changes the executable to Type: EXEC (Executable file) and keeps it at the intended 0x34800000 load address, SteamCMD then starts successfully.

So pass -no-pie whenever the Clang/mold link path uses the fixed Box64 image base. NOLOADADDR=ON remains an explicit opt-out, so builds that request an unfixed load address are unaffected.

Android is explicitly excluded because Android 5.0 and later require position-independent executables. The existing --image-base option remains unchanged for Android builds.

Verified as working with Clang/LLD and GCC + ld (GNU ld part is unchanged).

[ptitSeb]

Android builds are broken, because they need PIE...

[VoltrexKeyva]

Android builds are broken, because they need PIE...

Added a condition to keep PIE when targeting Android.