support -e entry flag

[TheButlah]

Disclaimer: I am a linker noob, there may be factual inaccuracies in my post.

I am attempting to build some OP-TEE Trusted Applet code, which targets aarch64-unknown-linux-gnu. I can do this successfully from my aarch64 laptop using regular cargo build. But if I attempt to use cargo zigbuild, I get an error:

[INFO ] error: linking with `/home/foobar/.cache/cargo-zigbuild/0.20.0/zigcc-aarch64-unknown-linux-gnu-7902.sh` failed: exit status: 1
[INFO ]   |
[INFO ]   = note:  "/home/foobar/.cache/cargo-zigbuild/0.20.0/zigcc-aarch64-unknown-linux-gnu-7902.sh" "<1 object files omitted>" "-Wl,--as-needed" "-Wl,-Bstatic" "-lutee" "-lutils" "/tmp/nix-shell.KCr8aT/rustcn3p3cV/liboptee_utee_sys-d570a50e488e6533.rlib" "/home/foobar/orb-software/optee/target/aarch64-unknown-linux-gnu/artifact/deps/libcompiler_builtins-75024177c013f69b.rlib" "-L" "/tmp/nix-shell.KCr8aT/rustcn3p3cV/raw-dylibs" "-Wl,-Bdynamic" "-Wl,--eh-frame-hdr" "-Wl,-z,noexecstack" "-L" "/home/foobar/orb-software/optee/target/aarch64-unknown-linux-gnu/artifact/build/orb-secure-storage-ta-809a613a6e90caab/out" "-L" "/nix/store/2kiqs9i1jyhq2y19z402xmj112jlz119-optee-os-vexpress-aarch64-unknown-linux-gnu-4.6.0-devkit/lib" "-L" "<sysroot>/lib/rustlib/aarch64-unknown-linux-gnu/lib" "-o" "/home/foobar/orb-software/optee/target/aarch64-unknown-linux-gnu/artifact/deps/orb_secure_storage_ta-2f59e169d44f48ef" "-Wl,--gc-sections" "-pie" "-Wl,-z,relro,-z,now" "-Wl,-O1" "-Wl,--strip-all" "-nodefaultlibs" "-T/home/foobar/orb-software/optee/target/aarch64-unknown-linux-gnu/artifact/build/orb-secure-storage-ta-809a613a6e90caab/out/ta.lds" "-e__ta_entry" "-pie" "-Os" "-Wl,--sort-section=alignment" "-Wl,--dynamic-list=dyn_list"
[INFO ]   = note: some arguments are omitted. use `--verbose` to show all linker arguments
[INFO ]   = note: error: Unknown Clang option: '-e__ta_entry'
[INFO ]
[INFO ]
[INFO ] error: could not compile `orb-secure-storage-ta` (bin "orb-secure-storage-ta") due to 1 previous error

I believe this is due to the -e__ta_entry flag, which is supposed to set the entry point of the program to be this function. It is generated by a build script here.

Is it in scope for cargo-zigbuild to handle this gcc linker argument?