Signed zero for {max,min}val intrinsics

Signed zero for {max,min}val intrinsics

The Fortran standard specifies (e.g. F2018 7.4.3.2) that intrinsic
procedures shall treat positive and negative real zero as equivalent,
unless it is explicitly specified otherwise.  For {max,min}val there
is no such explicit mention.  Thus, remove code to handle signed
zeros.

2018-08-23  Janne Blomqvist  <blomqvist.janne@gmail.com>

	* trans-intrinsic.c (gfc_conv_intrinsic_minmaxval): Delete
	HONOR_SIGNED_ZEROS checks.

From-SVN: r263802