cc/gcc: add option for linker hash style

Add an option to specify the hash type that gcc will ask the linker to use.
It is a provision for the upcoming 4.7, as no version currently supports it.

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;