ci: skip building and checking stage4 on riscv64-linux

ci/riscv64-linux-debug.sh

@@ -56,14 +56,3 @@ stage3-debug/bin/zig build test-cases test-modules test-unit test-standalone tes
   -Dtarget=native-native-musl \
   --search-prefix "$PREFIX" \
   --zig-lib-dir "$PWD/../lib"
-
-stage3-debug/bin/zig build \
-  --prefix stage4-debug \
-  -Denable-llvm \
-  -Dno-lib \
-  -Dtarget=$TARGET \
-  -Dcpu=$MCPU \
-  -Duse-zig-libcxx \
-  -Dversion-string="$(stage3-debug/bin/zig version)"
-
-stage4-debug/bin/zig test ../test/behavior.zig

ci/riscv64-linux-release.sh

@@ -56,20 +56,3 @@ stage3-release/bin/zig build test-cases test-modules test-unit test-standalone t
   -Dtarget=native-native-musl \
   --search-prefix "$PREFIX" \
   --zig-lib-dir "$PWD/../lib"
-
-# Ensure that stage3 and stage4 are byte-for-byte identical.
-stage3-release/bin/zig build \
-  --prefix stage4-release \
-  -Denable-llvm \
-  -Dno-lib \
-  -Doptimize=ReleaseFast \
-  -Dstrip \
-  -Dtarget=$TARGET \
-  -Dcpu=$MCPU \
-  -Duse-zig-libcxx \
-  -Dversion-string="$(stage3-release/bin/zig version)"
-
-# diff returns an error code if the files differ.
-echo "If the following command fails, it means nondeterminism has been"
-echo "introduced, making stage3 and stage4 no longer byte-for-byte identical."
-diff stage3-release/bin/zig stage4-release/bin/zig