Add --with-sysroot=/ to binutils recipe.

* on the bootstrap image, these binutils may be used by a gcc that's 
  passing --sysroot=<path> to ld, so we better configure ld to support 
  that

sys-devel/binutils/binutils-2.23.2_2013_04_09.recipe

@@ -3,7 +3,7 @@ HOMEPAGE="http://www.gnu.org/software/binutils"
 
 SRC_URI="
 	git+git://github.com/haiku/BuildtoolsPM.git#db2a6d28f6c6a92cfb1c619b0828dfbf6b87ca30"
-REVISION="1"
+REVISION="2"
 LICENSE="
 	GNU GPL v2
 	GNU LGPL v2
@@ -80,7 +80,11 @@ BUILD()
 		--exec-prefix=$installDir \
 		--includedir=$includeDir/binutils \
 		--docdir=$docDir \
-		--disable-nls --enable-shared=yes
+		--disable-nls --enable-shared=yes \
+		--with-sysroot=/
+		# Note: The sysroot option is normally superfluous. We have to specify
+		# it, however, since these binutils may be used by the bootstrap-gcc,
+		# which passes --sysroot=<path> to ld.
 
 	make $jobArgs
 }