Porting the configure script to C99

We're trying to build Fedora with a strict(er) C99 compiler:

  <https://fedoraproject.org/wiki/Changes/PortingToModernC>
  <https://fedoraproject.org/wiki/Toolchain/PortingToModernC>

Testing I dentified a couple of issues in the lynx configure script
(version 2.9.0dev.10 I believe):

diff --git a/aclocal.m4 b/aclocal.m4
index 70cde243d2129cc0..bf2cbff661de2fe1 100644
--- a/aclocal.m4
+++ b/aclocal.m4
@@ -6435,6 +6435,7 @@ AC_CACHE_CHECK(if we can include termio.h with curses,cf_cv_termio_and_curses,[
     CPPFLAGS="$CPPFLAGS -DHAVE_CONFIG_H -I. -I${srcdir:-.} -I${srcdir:-.}/src -I${srcdir:-.}/WWW/Library/Implementation"
     touch lynx_cfg.h
     AC_TRY_COMPILE([
+#include <stdio.h>
 #include <$1>
 #include <termio.h>],
     [putchar(0x0a)],
@@ -6455,6 +6456,7 @@ AC_DEFUN([CF_TERMIO_AND_TERMIOS],
 AC_MSG_CHECKING([termio.h and termios.h])
 AC_CACHE_VAL(cf_cv_termio_and_termios,[
     AC_TRY_COMPILE([
+#include <stdio.h>
 #if HAVE_TERMIO_H
 #include <termio.h>
 #endif
diff --git a/configure b/configure
index 97f6d1d5646d05c5..6db52b514b3b9a3c 100755
--- a/configure
+++ b/configure
@@ -31122,6 +31122,7 @@ else
 #line 31122 "configure"
 #include "confdefs.h"
 
+#include <stdio.h>
 #if HAVE_TERMIO_H
 #include <termio.h>
 #endif
@@ -31629,6 +31630,9 @@ else
 #line 31629 "configure"
 #include "confdefs.h"
 /* Thanks to Mike Rendell for this test.  */
+#if HAVE_UNISTD_H
+# include <unistd.h>
+#endif
 #include <sys/types.h>
 #define NGID 256
 #undef MAX
@@ -47492,6 +47496,7 @@ else
 #line 47492 "configure"
 #include "confdefs.h"
 
+#include <stdio.h>
 #include <LYCurses.h>
 #include <termio.h>
 int

The middle hunk in the configure patch is fixed in later autoconf
releases, it's not something that comes from aclocal.m4 or configure.in.

I'm sharing this here for the benefit of other distributions working on
similar projects.

Thanks,
Florian