Remove gcc spectre mitigation flags.

Current impementions of the gcc spectre mitigation flags cause
miscompilations when combined with other flags and do not provide much
protection.  Found by fweimer at redhat.com, ok djm@

1 files changed, 0 insertions, 9 deletions

diff --git a/configure.ac b/configure.ac
index 9dacccb2d..099ecdaa9 100644
--- a/configure.ac
+++ b/configure.ac
@@ -164,15 +164,6 @@ if test "$GCC" = "yes" || test "$GCC" = "egcs"; then
         OSSH_CHECK_CFLAG_COMPILE([-Wunused-result], [-Wno-unused-result])
         OSSH_CHECK_CFLAG_COMPILE([-fno-strict-aliasing])
     if test "x$use_toolchain_hardening" = "x1"; then
-        # Cygwin GCC 7.x allows thunking on the CLI, but produces non-working
-        # code.  Unfortunately you only notice this at link time.
-        case "$host" in
-        *-*-cygwin*) ;;
-        *)
-            OSSH_CHECK_CFLAG_COMPILE([-mfunction-return=thunk]) # gcc
-            OSSH_CHECK_CFLAG_COMPILE([-mindirect-branch=thunk]) # gcc
-            ;;
-        esac
         OSSH_CHECK_CFLAG_COMPILE([-mretpoline]) # clang
         OSSH_CHECK_LDFLAG_LINK([-Wl,-z,retpolineplt])
         OSSH_CHECK_CFLAG_COMPILE([-D_FORTIFY_SOURCE=2])