Darwin fix libstdc++ build warnings.

GCC does not export construction vtable symbols from shared libraries.

The symbols are marked hidden in the objects; for Darwin that makes
them also external (“private_extern” is Darwin’s hidden) which means
that they show up in the list of possible symbols for export from
libstdc++, and there are sufficiently relaxed match conditions that
they reach the exports list.   When Darwin’s static linker encounters
them it generates a warning that they cannot be exported.  This patch
prunes them from the list of symbols to be considered, thus
eliminating the warnings. No functional Change inended to the library

2018-12-06  Iain Sandoe  <iain@sandoe.co.uk>

	* scripts/make_exports.pl (check names): Don’t try to export
	construction vtable symbols.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@266864 138bc75d-0d04-0410-961f-82ee72b054a4
2 files changed