configure: portability fixes - take 2

It is useful to sometime run on a strictly POSIX-compliant
shell... :-/

And it is sometime interesting to refresh Q-patches before
finishing the series... :-(

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>

 --- binutils/ld/ldmain.c

 +++ binutils/ld/ldmain.c

 @@ -293,2 +293,3 @@ main (int argc, char **argv)

    link_info.combreloc = TRUE;

 +  link_info.relro = TRUE;

    link_info.strip_discarded = TRUE;