[PATCH] Cygwin: unbreak the build with GCC 7

[Ken Brown]

The recent port to GCC 8 used the 'nonstring' attribute, which is
unknown to GCC 7.  Define and use an 'ATTRIBUTE_NONSTRING' macro
instead.
---
 winsup/cygwin/include/sys/utmp.h | 11 ++++++++---
 winsup/cygwin/uname.cc           |  8 +++++++-
 2 files changed, 15 insertions(+), 4 deletions(-)
diff --git a/winsup/cygwin/include/sys/utmp.h b/winsup/cygwin/include/sys/utmp.h
index acf804ad0..443c44252 100644
--- a/winsup/cygwin/include/sys/utmp.h
+++ b/winsup/cygwin/include/sys/utmp.h
@@ -19,16 +19,21 @@ extern "C" {
 #define ut_name                ut_user
 #endif
 
+#if __GNUC__ >= 8
+#define ATTRIBUTE_NONSTRING __attribute__ ((nonstring))
+#else
+#define ATTRIBUTE_NONSTRING
+#endif
 
 struct utmp
 {
  short ut_type;
  pid_t ut_pid;
- char  ut_line[UT_LINESIZE] __attribute__ ((nonstring));
+ char  ut_line[UT_LINESIZE] ATTRIBUTE_NONSTRING;
  char  ut_id[UT_IDLEN];
  time_t ut_time;
- char  ut_user[UT_NAMESIZE] __attribute__ ((nonstring));
- char  ut_host[UT_HOSTSIZE] __attribute__ ((nonstring));
+ char  ut_user[UT_NAMESIZE] ATTRIBUTE_NONSTRING;
+ char  ut_host[UT_HOSTSIZE] ATTRIBUTE_NONSTRING;
  long  ut_addr;
 };
 
diff --git a/winsup/cygwin/uname.cc b/winsup/cygwin/uname.cc
index e323335b4..350216681 100644
--- a/winsup/cygwin/uname.cc
+++ b/winsup/cygwin/uname.cc
@@ -17,6 +17,12 @@ details. */
 extern "C" int cygwin_gethostname (char *__name, size_t __len);
 extern "C" int getdomainname (char *__name, size_t __len);
 
+#if __GNUC__ >= 8
+#define ATTRIBUTE_NONSTRING __attribute__ ((nonstring))
+#else
+#define ATTRIBUTE_NONSTRING
+#endif
+
 /* uname: POSIX 4.4.1.1 */
 
 /* New entrypoint for applications since API 335 */
@@ -25,7 +31,7 @@ uname_x (struct utsname *name)
 {
   __try
     {
-      char buf[NI_MAXHOST + 1] __attribute__ ((nonstring));
+      char buf[NI_MAXHOST + 1] ATTRIBUTE_NONSTRING;
       char *snp = strstr (cygwin_version.dll_build_date, "SNP");
 
       memset (name, 0, sizeof (*name));
-- 
2.21.0