Bug 12968: enable HEASLR in Windows x86_64 builds

We still need the other half of the fix for actually providing higher
entropy (see bug 12968, comment:17ff. for discussion).

rbm.conf

@@ -204,6 +204,8 @@ targets:
       container:
         arch: amd64
       faketime_path: /usr/lib/x86_64-linux-gnu/faketime/libfaketime.so.1
+      # HEASLR is 64 bit only (see bug 12968)
+      flag_HEASLR: '-Wl,--high-entropy-va'
   windows-i686:
     arch: i686
     var:
@@ -226,7 +228,7 @@ targets:
         suite: jessie
       configure_opt: '--host=[% c("arch") %]-w64-mingw32 CFLAGS="[% c("var/CFLAGS") %]" LDFLAGS="[% c("var/LDFLAGS") %]"'
       CFLAGS: '-fstack-protector-strong -fno-strict-overflow -Wno-missing-field-initializers -Wformat -Wformat-security [% c("var/flag_mwindows") %]'
-      LDFLAGS: '-Wl,--dynamicbase -Wl,--nxcompat -Wl,--enable-reloc-section -Wl,--no-insert-timestamp -lssp -L$gcclibs [% c("var/flag_mwindows") %]'
+      LDFLAGS: '-Wl,--dynamicbase -Wl,--nxcompat -Wl,--enable-reloc-section -Wl,--no-insert-timestamp -lssp -L$gcclibs [% c("var/flag_HEASLR") %] [% c("var/flag_mwindows") %]'
       flag_mwindows: '-mwindows'
       compiler: mingw-w64
       deps: