fix libtool 2.4.2 stack-protector flag handling

Teach libtool 2.4.2 how to pass -fstack-protector* to the linker so
libssp is properly linked in on some toolchains. See upstream patch:
https://github.com/instantinfrastructure/poky-daisy/blob/master/meta/recipes-devtools/libtool/libtool/respect-fstack-protector.patch

Thanks to kinichiro inoguchi

autogen.sh

@@ -4,3 +4,8 @@ set -e
 ./update.sh
 mkdir -p m4
 autoreconf -i -f
+
+# Patch libtool 2.4.2 to pass -fstack-protector as a linker argument
+sed 's/-fuse-linker-plugin)/-fuse-linker-plugin|-fstack-protector*)/' \
+  ltmain.sh > ltmain.sh.fixed
+mv -f ltmain.sh.fixed ltmain.sh

m4/check-hardening-options.m4

@@ -94,7 +94,9 @@ AC_DEFUN([CHECK_C_HARDENING_OPTIONS], [
 					AC_MSG_WARN([compiler does not appear to support stack protection])
 				)
 			)
-			AC_SEARCH_LIBS([__stack_chk_guard],[ssp])
+			AS_IF([test "x$HOST_OS" = "xwin"], [
+				AC_SEARCH_LIBS([__stack_chk_guard],[ssp])
+			])
 		])
 	])