Remove --size_t-is-usize from bindgen call

This has been on by default since
https://github.com/rust-lang/rust-bindgen/commit/cc78b6fdb6e829e5fb8fa1639f2182cb49333569,
and now removed from recent bindgen altogether.

Change-Id: Iea4c2a7480fe8b138c375686ca6b36e6d68257b3
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/58965
Reviewed-by: Nabil Wadih <nwadih@google.com>
Reviewed-by: Bob Beck <bbe@google.com>
Auto-Submit: David Benjamin <davidben@google.com>
Commit-Queue: Bob Beck <bbe@google.com>

rust/bssl-sys/CMakeLists.txt

diff --git a/rust/bssl-sys/CMakeLists.txt b/rust/bssl-sys/CMakeLists.txt
index 05f03f4..4cf8507 100644
--- a/rust/bssl-sys/CMakeLists.txt
+++ b/rust/bssl-sys/CMakeLists.txt
@@ -10,7 +10,6 @@
             --no-derive-default
             --enable-function-attribute-detection
             --use-core
-            --size_t-is-usize
             --default-macro-constant-type="signed"
             --rustified-enum="point_conversion_form_t"
             --allowlist-file=".*/include/openssl/.*\\.h"
@@ -35,4 +34,4 @@
   configure_file("build.rs" "build.rs" COPYONLY)
 endif()
 
-configure_file("Cargo.toml" "Cargo.toml" COPYONLY)
\ No newline at end of file
+configure_file("Cargo.toml" "Cargo.toml" COPYONLY)