message: Allow to set additional cmake options as environment variable.
  These can be picked up by the `cmake` invocations in the
  Makefile.
diff: @@ -16,6 +16,7 @@ ifeq ($(CPU_CORES),)
  endif
  PREFIX ?= /usr/local
  +ADDITIONAL_CMAKE_OPTIONS ?=
  # If 'on', then the progress messages are printed. If 'off', makes it easier
  # to detect actual warnings and errors in the build output.
  @@ -31,16 +32,16 @@ debug: run-cmake-debug
  cmake --build dbuild -j $(CPU_CORES)
  run-cmake-release:
  - cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=$(PREFIX) -DCMAKE_RULE_MESSAGES=$(RULE_MESSAGES) -S . -B build
  + cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=$(PREFIX) -DCMAKE_RULE_MESSAGES=$(RULE_MESSAGES) $(ADDITIONAL_CMAKE_OPTIONS) -S . -B build
  run-cmake-release_no_tcmalloc:
  - cmake -DNO_TCMALLOC=On -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=$(PREFIX) -DCMAKE_RULE_MESSAGES=$(RULE_MESSAGES) -S . -B build
  + cmake -DNO_TCMALLOC=On -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=$(PREFIX) -DCMAKE_RULE_MESSAGES=$(RULE_MESSAGES) $(ADDITIONAL_CMAKE_OPTIONS) -S . -B build
  run-cmake-debug:
  - cmake -DCMAKE_BUILD_TYPE=Debug -DCMAKE_INSTALL_PREFIX=$(PREFIX) -DCMAKE_RULE_MESSAGES=$(RULE_MESSAGES) -DNO_TCMALLOC=On -S . -B dbuild
  + cmake -DCMAKE_BUILD_TYPE=Debug -DCMAKE_INSTALL_PREFIX=$(PREFIX) -DCMAKE_RULE_MESSAGES=$(RULE_MESSAGES) -DNO_TCMALLOC=On $(ADDITIONAL_CMAKE_OPTIONS) -S . -B dbuild
  run-cmake-coverage:
  - cmake -DCMAKE_BUILD_TYPE=Debug -DCMAKE_INSTALL_PREFIX=$(PREFIX) -DCMAKE_RULE_MESSAGES=$(RULE_MESSAGES) -DMY_CXX_WARNING_FLAGS="--coverage" -S . -B coverage-build
  + cmake -DCMAKE_BUILD_TYPE=Debug -DCMAKE_INSTALL_PREFIX=$(PREFIX) -DCMAKE_RULE_MESSAGES=$(RULE_MESSAGES) -DMY_CXX_WARNING_FLAGS="--coverage" $(ADDITIONAL_CMAKE_OPTIONS) -S . -B coverage-build
  test/unittest: run-cmake-release
  cmake --build build --target UnitTests -j $(CPU_CORES)
  