Remove unused pybind copts

Since this target has no srcs these are unused

Author: keith

pybind11-BUILD.bazel

@@ -20,10 +20,6 @@ cc_library(
         ":msvc_compiler": [],
         "//conditions:default": [
             "-fexceptions",
-            # Useless warnings
-            "-Xclang-only=-Wno-undefined-inline",
-            "-Xclang-only=-Wno-pragma-once-outside-header",
-            "-Xgcc-only=-Wno-error",  # no way to just disable the pragma-once warning in gcc
         ],
     }),
     includes = ["include"],