Compiler warns about initializing reference with temporary in astrocyte_lr_1994

[heplesser]

The newest AppleClang (15.0.0.15000309) warns about assigning the result of a temporary expression evaluation result to a reference:

nest-simulator/models/astrocyte_lr_1994.cpp

Lines 84 to 89 in 5639572

	// shorthand for state variables
	const double& ip3 = y[ S::IP3 ];
	// Ca_tot_ corresponds to the c_0 (total [Ca++] in terms of cytosolic vol)
	// in De Young & Keizer (1992) and Li & Rinzel (1994)
	const double& calc = std::max( 0.0, std::min( y[ S::Ca_astro ], node.P_.Ca_tot_ ) ); // keep calcium within limits
	const double& h_ip3r = y[ S::h_IP3R ];

conc should be a proper variable. The two references above and below are fine, since they point to vector elements.