Add a config option for default RELRO setting

Fixes #656.

Signed-off-by: Alexey Neyman <stilor@att.net>

config/binutils/binutils.in

@@ -146,6 +146,16 @@ config BINUTILS_PLUGINS
       Especially, gold can use the lto-plugin, as installed
       by gcc, to handle LTO.
 
+config BINUTILS_RELRO
+    tristate
+    prompt "Enable -z relro in ELF linker by default" if BINUTILS_2_27_or_later
+    default m
+    help
+      Setting this option forces "-z relro" by default in the ELF linker.
+      Clearing this option forces "-z norelro" by default in the ELF linker.
+      Setting this option to 'M' configures binutils with their internal
+      default for the selected architecture.
+
 config BINUTILS_EXTRA_CONFIG_ARRAY
     string
     prompt "binutils extra config"

packages/binutils/package.desc

@@ -1,6 +1,6 @@
 repository='git git://sourceware.org/git/binutils-gdb.git'
 mirrors='$(CT_Mirrors GNU binutils) $(CT_Mirrors sourceware binutils/releases)'
 origin='GNU'
-milestones='2.23 2.25 2.30'
+milestones='2.23 2.25 2.27 2.30'
 archive_formats='.tar.xz .tar.bz2 .tar.gz'
 signature_format='packed/.sig'

scripts/build/binutils/binutils.sh

@@ -153,6 +153,11 @@ do_binutils_backend() {
     if [ "${CT_BINUTILS_PLUGINS}" = "y" ]; then
         extra_config+=( --enable-plugins )
     fi
+    if [ "${CT_BINUTILES_RELRO}" = "y" ]; then
+        extra_config+=( --enable-relro )
+    elif [ "${CT_BINUTILS_RELRO}" != "m" ]; then
+        extra_config+=( --disable-relro )
+    fi
     if [ "${CT_BINUTILS_HAS_PKGVERSION_BUGURL}" = "y" ]; then
         [ -n "${CT_PKGVERSION}" ] && extra_config+=("--with-pkgversion=${CT_PKGVERSION}")
         [ -n "${CT_TOOLCHAIN_BUGURL}" ] && extra_config+=("--with-bugurl=${CT_TOOLCHAIN_BUGURL}")