patch 8.1.0824: SunOS/Solaris has a problem with ttys

Problem:    SunOS/Solaris has a problem with ttys.
Solution:   Add mch_isatty() with extra handling for SunOS. (Ozaki Kiichi,
            closes #3865)
diff --git a/src/configure.ac b/src/configure.ac
index e5525ea..2b7725b 100644
--- a/src/configure.ac
+++ b/src/configure.ac
@@ -3265,7 +3265,7 @@
 	unistd.h stropts.h errno.h sys/resource.h \
 	sys/systeminfo.h locale.h sys/stream.h termios.h \
 	libc.h sys/statfs.h poll.h sys/poll.h pwd.h \
-	utime.h sys/param.h libintl.h libgen.h \
+	utime.h sys/param.h sys/ptms.h libintl.h libgen.h \
 	util/debug.h util/msg18n.h frame.h sys/acl.h \
 	sys/access.h sys/sysinfo.h wchar.h wctype.h)