fix(android): drop pthread_shim — clang shim makes it unnecessary (and harmful)

Once the Dockerfile rewrites every android24-clang to exec android26-clang,
the linker uses the API-26 NDK sysroot and libstd's pthread_create reference
resolves directly against libc.so's real runtime symbol — no interposition
needed.

The pthread_shim.c approach was actually fighting its own solution: our
shim's dlsym() call bound at link time to libdl.a's STUB dlsym (a
five-line function inside libdl_static.o that just returns NULL and sets
dlerror to "libdl.a is a stub --- use libdl.so instead"). NDK r19 and
glibc 2.34 both replaced libdl.a with empty stubs because dynamic loading
is now part of the main libc/bionic — so no amount of link-order
tinkering can make a static libdl.a dlsym actually work.

Remove pthread_shim.c, the cc::Build::new().file("cpp/pthread_shim.c")
step in build.rs, and the -Wl,--wrap=pthread_create rustc-link-arg. Keep
getauxval_fix.c because that one DOES work at link time (the symbol
override is for a function compiler-rt defines statically, not one that
would depend on the stub libdl.a/libc.a).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

desktop/src-tauri/build.rs

@@ -38,14 +38,6 @@ fn build_oboe_android(target: &str) {
         .file("cpp/getauxval_fix.c")
         .compile("getauxval_fix");
 
-    // pthread_shim: interpose pthread_create so Rust libstd can't use the
-    // broken static pthread_create stub (which calls __init_tcb, crashing
-    // in a .so). Our shim forwards to libc.so's real one via RTLD_NEXT.
-    // Compiled as its own static lib so the linker links it ahead of libstd.
-    cc::Build::new()
-        .file("cpp/pthread_shim.c")
-        .compile("pthread_shim");
-
     let oboe_dir = fetch_oboe();
     match oboe_dir {
         Some(oboe_path) => {
@@ -112,12 +104,6 @@ fn build_oboe_android(target: &str) {
     // Oboe requires Android log + OpenSLES backends
     println!("cargo:rustc-link-lib=log");
     println!("cargo:rustc-link-lib=OpenSLES");
-
-    // Wrap pthread_create: redirect every `pthread_create` reference to our
-    // `__wrap_pthread_create` in pthread_shim.c, which forwards to the real
-    // libc.so symbol via dlsym. Without this the linker binds to libstd's
-    // bundled broken static pthread_create stub (see pthread_shim.c).
-    println!("cargo:rustc-link-arg=-Wl,--wrap=pthread_create");
 }
 
 /// Recursively add all .cpp files from a directory to a cc::Build.