Use -fno-show-column in libstdc++ installed testing.
<https://gcc.gnu.org/ml/libstdc++/2016-08/msg00006.html> arranged for
libstdc++ tests to use -fno-show-column by default, but only for
build-tree testing. This patch adds it to the options used for
installed testing as well.
Tested with installed testing for a cross to x86_64-linux-gnu, where
it fixes various test failures.
* testsuite/lib/libstdc++.exp (libstdc++_init): Use
-fno-show-column in default cxxflags.
git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@264784 138bc75d-0d04-0410-961f-82ee72b054a4