alignof is a C23 keyword

git-svn-id: https://svn.r-project.org/R/trunk@87686 00db46b3-68df-0310-9c12-caf00c1e9a41

Author: ripley

src/extra/intl/dcigettext.c

@@ -123,7 +123,9 @@ extern int errno;
 #endif
 
 /* Alignment of types.  */
-#if defined __GNUC__ && __GNUC__ >= 2
+// R change: alignof is a keyword in C23
+#if defined __STDC_VERSION__ && __STDC_VERSION__ > 201710L
+#elif defined __GNUC__ && __GNUC__ >= 2
 # define alignof(TYPE) __alignof__ (TYPE)
 #else
 /* R change: was (int) */