Add C backend - close #4

spec/testutils.h

@@ -0,0 +1,19 @@
+#pragma once
+
+void assert_eq_size_t_i(size_t expected, size_t actual, char const * file, size_t line);
+
+#define assert_eq(expected, actual) \
+    assert_eq_size_t_i(expected, actual, __FILE__, __LINE__)
+
+typedef struct
+{
+    char * cs;
+} str_t;
+
+void str_init(str_t * str, char const * cs);
+void str_append(str_t * str, char const * cs);
+void str_free(str_t * str);
+static inline char * str_cstr(str_t * str)
+{
+    return str->cs;
+}