PR d/90059
	PR d/90060
	PR d/90062
libphobos: Merge upstream druntime 70b9fea6

Backports fixes in the extern(C) bindings for the Solaris/SPARC port.

Initial patch by Rainer Orth.

Reviewed-on: https://github.com/dlang/druntime/pull/2555

From-SVN: r270372