TLS-related functions (`__aeabi_read_tp`, `__tls_get_addr`) are not introduced
to bionic libc until Android 10. `__builtin_thread_pointer` will omit calls to
`__aeabi_read_tp` on arm, and causes build failure when `__ANDROID_API__` < 29.

TLS slot 1 has been used to storage thread id since Android 1.6 [1], and hasn't
changed until Android 14 [2,3]. If `__builtin_thread_pointer` is not available,
the default code path uses the method mentioned above to obtain a unique thread
id, and there doesn't seem to be anything wrong with this. If necessary in the
future, other methods can be made up for it, such as calling `pthread_self`.

Besides, force using Emulated TLS for better compatibility.

[1]: https://android.googlesource.com/platform/bionic/+/refs/tags/android-1.6_r1/libc/private/bionic_tls.h#57
[2]: https://android.googlesource.com/platform/bionic/+/refs/heads/android14-dev/libc/platform/bionic/tls_defines.h#86
[3]: https://android.googlesource.com/platform/bionic/+/refs/heads/android14-dev/libc/platform/bionic/tls_defines.h#106

The error message is as follows.

```
  = note: ld.lld: error: undefined symbol: __aeabi_read_tp
          >>> referenced by static.c
          >>>               98cfcaec7182b1d8-static.o:(mi_free) in archive /tmp/rustcp5Rvgx/liblibmimalloc_sys-7086a69efa004ab8.rlib
          >>> referenced by static.c
          >>>               98cfcaec7182b1d8-static.o:(_mi_arena_segment_clear_abandoned) in archive /tmp/rustcp5Rvgx/liblibmimalloc_sys-7086a69efa004ab8.rlib
          >>> referenced by static.c
          >>>               98cfcaec7182b1d8-static.o:(_mi_arena_segment_clear_abandoned) in archive /tmp/rustcp5Rvgx/liblibmimalloc_sys-7086a69efa004ab8.rlib
          >>> referenced 9 more times
          clang-17: error: linker command failed with exit code 1 (use -v to see invocation)
```

--- a/build.rs
+++ b/build.rs
@@ -25,7 +25,10 @@ fn main() {
 
     let dynamic_tls = env::var("CARGO_FEATURE_LOCAL_DYNAMIC_TLS").is_ok();
 
-    if target_family == "unix" && target_os != "haiku" {
+    if target_family == "unix" && target_os == "android" {
+        build.flag_if_supported("-femulated-tls");
+    }
+    else if target_family == "unix" && target_os != "haiku" {
         if dynamic_tls {
             build.flag_if_supported("-ftls-model=local-dynamic");
         } else {
--- a/c_src/mimalloc/include/mimalloc/prim.h
+++ b/c_src/mimalloc/include/mimalloc/prim.h
@@ -211,6 +212,7 @@
 #if defined(__GNUC__) && (__GNUC__ >= 7) && defined(__aarch64__) /* special case aarch64 for older gcc versions (issue #851) */ \
     && !defined(__APPLE__)  /* on apple (M1) the wrong register is read (tpidr_el0 instead of tpidrro_el0) so fall back to TLS slot assembly (<https://github.com/microsoft/mimalloc/issues/343#issuecomment-763272369>)*/ \
     && (!defined(__clang_major__) || __clang_major__ >= 14)  /* older clang versions emit bad code; fall back to using the TLS slot (<https://lore.kernel.org/linux-arm-kernel/202110280952.352F66D8@keescook/T/>) */
+    && (!defined(__ANDROID__) || __ANDROID_API__ >= 29) /* __builtin_thread_pointer will omit calls to __aeabi_read_tp on arm Android, and causes build failure when __ANDROID_API__ < 29 */
 #define MI_USE_BUILTIN_THREAD_POINTER  1
 #endif