Fix Ada runtime library breakage on Solaris

Fix Ada runtime library breakage on Solaris

The recent changes made to the runtime library broke its build on Solaris
because it uses Solaris threads instead of POSIX threads on this platform.

gcc/ada/
	PR ada/115133
	* libgnarl/s-osinte__solaris.ads (mutex_t): Fix typo.
	* libgnarl/s-taprop__solaris.adb (Record_Lock): Add conversion.
	(Check_Sleep): Likewise.
	(Record_Wakeup): Likewise.
	(Check_Unlock): Likewise.
	* libgnarl/s-tasini.adb (Initialize_RTS_Lock): Add pragma Import
	on the overlaid variable.
	(Finalize_RTS_Lock): Likewise.
	(Acquire_RTS_Lock): Likewise.
	(Release_RTS_Lock): Likewise.
	* libgnarl/s-taspri__solaris.ads (To_RTS_Lock_Ptr): New instance
	of Ada.Unchecked_Conversion.
	* libgnat/s-oslock__solaris.ads: Add with clause for
	Ada.Unchecked_Conversion.
	(array_type_9): Add missing name qualification.
	(record_type_3): Likewise.
	(mutex_t): Fix formatting.