Fix p_cs_precedes, n_cs_precedes, and n_sign_posn for mt_MT

Positive Currency Format: €500.00
Negative Currency Format: -€500.00
References:
http://www.kunsilltalmalti.gov.mt/filebank/documents/rapportdwarlismijiettalmunitaewropea.pdf, page 7, top right.
CLDR has “¤#,##0.00” as the currency format pattern.

	[BZ #21920]
	* locales/mt_MT (LC_MONETARY): Fix p_cs_precedes/n_cs_precedes.
	* locales/mt_MT (LC_MONETARY): Fix n_sign_posn.