-Wl,-z,relro and -z,now were wiping out environmental LDFLAGS passed in by the user.

I moved them to HARDENING_* where they belong.

configure.ac

@@ -303,8 +303,8 @@ if test x$use_hardening != xno; then
 
   AX_CHECK_LINK_FLAG([[-Wl,--dynamicbase]], [HARDENED_LDFLAGS="$HARDENED_LDFLAGS -Wl,--dynamicbase"])
   AX_CHECK_LINK_FLAG([[-Wl,--nxcompat]], [HARDENED_LDFLAGS="$HARDENED_LDFLAGS -Wl,--nxcompat"])
-  AX_CHECK_LINK_FLAG([[-Wl,-z,relro]], [LDFLAGS="-Wl,-z,relro"])
-  AX_CHECK_LINK_FLAG([[-Wl,-z,now]], [LDFLAGS="-Wl,-z,now"])
+  AX_CHECK_LINK_FLAG([[-Wl,-z,relro]], [HARDENED_LDFLAGS="$HARDENED_LDFLAGS -Wl,-z,relro"])
+  AX_CHECK_LINK_FLAG([[-Wl,-z,now]], [HARDENED_LDFLAGS="$HARDENED_LDFLAGS -Wl,-z,now"])
 
   if test x$TARGET_OS != xwindows; then
     # -pie will link successfully with MinGW, but it's unsupported and leads to undeterministic binaries