Compiles the regular expression to an internal form, and does the initial setup of the GRegex structure.
| pattern | the regular expression |
| compile_options | compile options for the regular expression, or 0 |
| match_options | match options for the regular expression, or 0 |
| error | return location for a GError |
| a GRegex structure. Call g_regex_unref() when you are done with it |