This handles both integer and floating-point arguments.  It's needed
for the follow-on patch to move fmin and fmax to match.pd.

Tested on x86_64-linux-gnu, aarch64-linux-gnu and arm-linux-gnueabi.

gcc/
	* fold-const.c (fold_minmax): Delete.
	(fold_binary_loc): Don't call it.
	* match.pd: Add rules previously handled by fold_minmax.

From-SVN: r229430