i586-pc-nto-qnx700 doesn't work because of missing cfg-if branch for 32-bit x86

[jonathanpallant]

Trying to build i586-pc-nto-qnx700 with this script:

#!/bin/bash
source ~/qnx700/qnxsdp-env.sh
export build_env='
         CC_aarch64_unknown_nto_qnx700=qcc
        CXX_aarch64_unknown_nto_qnx700=qcc
     CFLAGS_aarch64_unknown_nto_qnx700=-Vgcc_ntoaarch64le_cxx
         AR_aarch64_unknown_nto_qnx700=ntoaarch64-ar
         CC_i586_pc_nto_qnx700=qcc
        CXX_i586_pc_nto_qnx700=qcc
     CFLAGS_i586_pc_nto_qnx700=-Vgcc_ntox86_cxx
         AR_i586_pc_nto_qnx700=ntox86-ar
'

env $build_env ./x.py build \
  --target aarch64-apple-darwin,aarch64-unknown-nto-qnx700,i586-pc-nto-qnx700 \
  rustc library/core library/alloc library/std src/tools/remote-test-server

produces this error:

error[E0432]: unresolved imports `crate::c_char`, `crate::c_long`, `crate::c_ulong`
   --> /Users/jonathan/.cargo/registry/src/index.crates.io-6f17d22bba15001f/libc-0.2.169/src/macros.rs:84:17
    |
65  | / macro_rules! prelude {
66  | |     () => {
67  | |         /// Frequently-used types that are available on all platforms
68  | |         ///
...   |
84  | |                 c_char, c_double, c_float, c_int, c_long, c_longlong, c_short, c_uchar, c_uint,
    | |                 ^^^^^^                            ^^^^^^ no `c_long` in the root
    | |                 |
    | |                 no `c_char` in the root
    | |                 help: a similar name exists in the module: `c_schar`
85  | |                 c_ulong, c_ulonglong, c_ushort, c_void, intptr_t, size_t, ssize_t, uintptr_t,
    | |                 ^^^^^^^ no `c_ulong` in the root
...   |
88  | |     };
89  | | }
    | |_- in this expansion of `prelude!`
    |
   ::: /Users/jonathan/.cargo/registry/src/index.crates.io-6f17d22bba15001f/libc-0.2.169/src/lib.rs:138:9
    |
138 |           prelude!();
    |           ---------- in this macro invocation
    |
    = help: consider importing this type alias instead:
            rustc_std_workspace_core::ffi::c_char
    = help: consider importing this type alias instead:
            rustc_std_workspace_core::ffi::c_long
    = help: consider importing this type alias instead:
            rustc_std_workspace_core::ffi::c_ulong

Building the aarch64 target works.

I believe the fault lies in this block, which is missing a branch for x86.

cfg_if! {
    if #[cfg(target_arch = "x86_64")] {
        mod x86_64;
        pub use self::x86_64::*;
    } else if #[cfg(target_arch = "aarch64")] {
        mod aarch64;
        pub use self::aarch64::*;
    } else {
        panic!("Unsupported arch");
    }
}