Turn ivory-examples generic-test from removed Makefile to a test-suite

[sorki]

Has to be guarded by a flag since it requires gcc

.PHONY: generic-test
generic-test: default
    $(STACK_CMD) build --test --no-run-tests --haddock --no-haddock-deps --pedantic
    $(STACK_CMD) test $(TEST_TARGETS)
    $(STACK_CMD) exec -- ivory-c-clang-test $(IVORY_EX_TEST_DIR)
    cp ivory-examples/data/*.h $(IVORY_EX_TEST_DIR)/
    cd $(IVORY_EX_TEST_DIR) &&          \
        gcc -Wall -Wextra -Werror       \
            -Wno-missing-field-initializers \
            -Wno-unused-parameter       \
            -Wno-unused-variable        \
            -DIVORY_DEPLOY -I. -std=c99 -c  \
            *.c *.h