[Bug other/63758] liblto_plugin.so has undefined reference to _environ on OSX

[roland at gnu dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63758

--- Comment #1 from roland at gnu dot org ---
Created attachment 33903
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=33903&action=edit
proposed patch

This patch fixes it on OSX.  I haven't verified it on a wide variety of
configurations.