mlib gcc5

Author: dkm

.github/workflows/ccpp.yml

@@ -89,10 +89,10 @@ jobs:
         uses: ./.github/actions/build-gcc
         with:
           extra-configure-env: ''
-          run_test_flags: '--target_board=unix\{-m32}'
+          run_test_flags: '--target_board=unix\{-m32,-m64}'
           glibc_assertion: false
           use-old-gcc: '5.4.0'
-          enable_multilib: false
+          enable_multilib: true
           bootstrap: false
 
   build-and-check-asan: