Empties builder and frees its extra buffers so it can be used again.
reset :: (builder: *String_Builder)Parameters
- builder: *String_Builder
builder: String_Builder;
defer free_buffers(*builder);
append(*builder, "old");
reset(*builder);
append(*builder, "new");
text := builder_to_string(*builder);
defer free(text);
assert(text == "new");