ZJIT: Set ZJIT_RB_BUG to help debugging CI issues (ruby#14500)

Author: st0012

.github/workflows/zjit-macos.yml

@@ -51,6 +51,7 @@ jobs:
       RUN_OPTS: ${{ matrix.run_opts }}
       SPECOPTS: ${{ matrix.specopts }}
       TESTOPTS: ${{ matrix.testopts }}
+      ZJIT_RB_BUG: 1
 
     runs-on: macos-14
 

.github/workflows/zjit-ubuntu.yml

@@ -75,6 +75,7 @@ jobs:
       RUBY_DEBUG: ci
       BUNDLE_JOBS: 8 # for yjit-bench
       RUST_BACKTRACE: 1
+      ZJIT_RB_BUG: 1
 
     runs-on: ubuntu-22.04