Re: 2019Q4 gcc7 build failure on illumos

[Zhiwen Zheng <zhiwen%40701.xyz@localhost>]

This failure is caused by passing the "-lrt" option to readelf, readelf does not understand that and failed out.
This is a gcc bug, illumos' gcc port has a fix ( https://u8209486.ct.sendgrid.net/ls/click?upn=5-2BjrOL6Sde2a9aQLMiEgaIjltaRszc4rC6AXXvtiib3Zsdq2MSNebcGJ6GLcgymmhLpaRUdRxQwwi1mFeUKzF2SZuby7XxMkI8ijpr-2BjzSQwOFEbaSxnnqQDdhNLdTdkkbPb_9zlmVlpiNfLqy8Jl6Xjd4VEcG5KtN2wMRe2-2B8KIsz6cEvtHz-2FkBeSYdNJsDFRDEpsfJ-2BMCrGKjqbqqvbcaiRgLpzb8rMCNsliYbHQFFAEx5yArhQC6mwMyQEYru77H-2FIt0wpoanzLweMI6r8YJv-2FX4GGzOhoPVekQtGD7i4rqxzli7hFwVtIUVpy5v3QBziuGVJUSUG7aQBfoQihDcOZORe-2F4O2anTReCILHkxi-2BRX1TMq4t69Yp6SQ-2FKTYVw5p1

I applied that patch to pkgsrc and gcc7 builds fine.

The patches are attched below, can we integrate it to the pkgsrc-2019Q4 branch?

-bash-4.3# cat patches/patch-libstdc++-v3_acinclude.m4 
$NetBSD$

--- libstdc++-v3/acinclude.m4.orig	2020-03-09 15:43:49.217108714 +0000
+++ libstdc++-v3/acinclude.m4
@@ -1434,7 +1434,6 @@ AC_DEFUN([GLIBCXX_ENABLE_LIBSTDCXX_TIME]
         ac_has_nanosleep=yes
         ;;
       solaris*)
-        GLIBCXX_LIBS="$GLIBCXX_LIBS -lrt"
         ac_has_clock_monotonic=yes
         ac_has_clock_realtime=yes
         ac_has_nanosleep=yes


-bash-4.3# cat patches/patch-libstdc++-v3_configure
$NetBSD$

--- libstdc++-v3/configure.orig	2020-03-09 15:44:03.844191740 +0000
+++ libstdc++-v3/configure
@@ -20578,7 +20578,6 @@ $as_echo "$glibcxx_glibc217" >&6; }
         ac_has_nanosleep=yes
         ;;
       solaris*)
-        GLIBCXX_LIBS="$GLIBCXX_LIBS -lrt"
         ac_has_clock_monotonic=yes
         ac_has_clock_realtime=yes
         ac_has_nanosleep=yes