Make libbz2-rs-sys-cdylib unconditionally no_std

This reduces the size of libbz2_rs.so by 408KB in release mode.

libbzip2-rs-sys-cdylib/Cargo.toml

@@ -15,9 +15,8 @@ name = "bz2_rs" # turns into e.g. `libbz2_rs.so`
 crate-type=["cdylib"]
 
 [features]
-default = ["c-allocator", "libbzip2-rs-sys/stdio",  "libbzip2-rs-sys/std"] # when used as a cdylib crate, use the c allocator
+default = ["c-allocator", "libbzip2-rs-sys/stdio"] # when used as a cdylib crate, use the c allocator
 c-allocator = ["libbzip2-rs-sys/c-allocator"] # by default, use malloc/free for memory allocation
-rust-allocator = ["libbzip2-rs-sys/rust-allocator", "libbzip2-rs-sys/std"] # by default, use the rust global alloctor for memory allocation
 custom-prefix = ["libbzip2-rs-sys/custom-prefix"] # use the LIBBZIP2_RS_SYS_PREFIX to prefix all exported symbols
 capi = []
 
@@ -34,3 +33,10 @@ enabled = false
 [package.metadata.capi.pkg_config]
 name = "libbz2_rs"
 filename = "libbz2_rs"
+
+# no_std requires panic=abort
+[profile.dev]
+panic = "abort"
+
+[profile.release]
+panic = "abort"

libbzip2-rs-sys-cdylib/src/lib.rs

@@ -1,3 +1,17 @@
+#![no_std]
+
 extern crate libbzip2_rs_sys;
 
+use core::ffi::c_int;
+use core::panic::PanicInfo;
 pub use libbzip2_rs_sys::*;
+
+#[panic_handler]
+fn panic_handler(_info: &PanicInfo) -> ! {
+    extern "C" {
+        fn bz_internal_error(errcode: c_int);
+    }
+
+    unsafe { bz_internal_error(-1) }
+    loop {}
+}