remove ext_package so top_level.txt is accurate in wheel metadata (#7511)

setup.cfg

@@ -43,7 +43,6 @@ zip_safe = False
 package_dir =
     =src
 packages = find:
-ext_package = cryptography.hazmat.bindings
 # `install_requires` must be kept in sync with `pyproject.toml`
 install_requires =
     cffi >=1.12

setup.py

@@ -45,7 +45,7 @@ try:
         ],
         rust_extensions=[
             RustExtension(
-                "_rust",
+                "cryptography.hazmat.bindings._rust",
                 "src/rust/Cargo.toml",
                 py_limited_api=True,
                 # Enable abi3 mode if we're not using PyPy.

src/_cffi_src/build_openssl.py

@@ -70,7 +70,7 @@ def _extra_compile_args(platform):
 
 
 ffi = build_ffi_for_binding(
-    module_name="_openssl",
+    module_name="cryptography.hazmat.bindings._openssl",
     module_prefix="_cffi_src.openssl.",
     modules=[
         # This goes first so we can define some cryptography-wide symbols.