Use C23 on Windows for standalone nmath.

git-svn-id: https://svn.r-project.org/R/trunk@87954 00db46b3-68df-0310-9c12-caf00c1e9a41

Author: kalibera

src/nmath/standalone/Makefile.win

@@ -1,7 +1,7 @@
 #-*- Makefile -*-
 include ../../gnuwin32/MkRules
 
-CFLAGS = -O3 -Wall -pedantic $(EOPTS)
+CFLAGS = -O3 -Wall -pedantic $(CSTD) $(EOPTS)
 ifdef DEBUG
  CFLAGS += $(G_FLAG)
  DLLFLAGS =