Add Coveralls integration

Build and upload lcov-compatible coverage file to coveralls

.github/workflows/build.yml

@@ -69,6 +69,11 @@ jobs:
     - name: make coverage
       run: |
         CXX=clang++-10 make -j2 config=coverage coverage
+    - name: upload coverage
+      uses: coverallsapp/github-action@master
+      with:
+        path-to-lcov: ./coverage.info
+        github-token: ${{ secrets.GITHUB_TOKEN }}
     - uses: actions/upload-artifact@v2
       with:
         name: coverage

Makefile

@@ -107,6 +107,7 @@ coverage: $(TESTS_TARGET)
 	rm default.profraw default-flags.profraw
 	llvm-cov show -format=html -show-instantiations=false -show-line-counts=true -show-region-summary=false -ignore-filename-regex=\(tests\|extern\)/.* -output-dir=coverage --instr-profile default.profdata build/coverage/luau-tests
 	llvm-cov report -ignore-filename-regex=\(tests\|extern\)/.* -show-region-summary=false --instr-profile default.profdata build/coverage/luau-tests
+	llvm-cov export -ignore-filename-regex=\(tests\|extern\)/.* -format lcov --instr-profile default.profdata build/coverage/luau-tests >coverage.info
 
 format:
 	find . -name '*.h' -or -name '*.cpp' | xargs clang-format -i