mail/mozilla-thunderbird: drop patch from #1874059, merged upstream

reminded by naddy@, mishap between cvs and local git..

mail/mozilla-thunderbird/patches/patch-build_moz_configure_toolchain_configure

@@ -1,16 +0,0 @@
-https://bugzilla.mozilla.org/show_bug.cgi?id=1874059
-https://github.com/llvm/llvm-project/issues/79027
-https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=276746
-
-Index: build/moz.configure/toolchain.configure
---- build/moz.configure/toolchain.configure.orig
-+++ build/moz.configure/toolchain.configure
-@@ -2290,7 +2290,7 @@ set_define("_LIBCPP_HIDE_FROM_ABI", libcxx_override_vi
- @depends(target, build_environment)
- def visibility_flags(target, env):
-     if target.os != "WINNT":
--        if target.kernel == "Darwin":
-+        if target.kernel == "Darwin" or target.kernel == "OpenBSD":
-             return ("-fvisibility=hidden", "-fvisibility-inlines-hidden")
-         return (
-             "-I%s/system_wrappers" % os.path.join(env.dist),