https://sourceforge.net/p/xine/tickets/22/
https://bugs.gentoo.org/899872

Fix C compatibility issues in the configure script

This is necessary to avoid incorrectly failing probes due to expected
compiler errors.

Include <stdlib.h> for the exit function, and <string.h> for the
strdup function.

Use fake prototypes to avoid implicit function declarations in the
xine_* function probes.

--- a/configure.ac
+++ b/configure.ac
@@ -198,6 +198,7 @@
   if test "$ac_cv_header_sys_shm_h" = "yes"; then
     AC_MSG_CHECKING(whether shmctl IPC_RMID allowes subsequent attaches)
     AC_TRY_RUN([
+	  #include <stdlib.h>
           #include <sys/types.h>
           #include <sys/ipc.h>
           #include <sys/shm.h>
--- a/m4/aa.m4
+++ b/m4/aa.m4
@@ -52,6 +52,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <aalib.h>
+#include <string.h>
 
 int main () {
   int major, minor;
--- a/m4/_xine.m4
+++ b/m4/_xine.m4
@@ -218,7 +218,7 @@
      CFLAGS="$CFLAGS $XINE_CFLAGS"
      LIBS="$LIBS $XINE_LIBS"
      AC_LINK_IFELSE(
-         [AC_LANG_PROGRAM([],[xine_open_cloexec();])],
+         [AC_LANG_PROGRAM([char xine_open_cloexec(void);],[xine_open_cloexec();])],
          [AC_DEFINE([HAVE_XINE_OPEN_CLOEXEC], [1], [Define if xine-lib supports xine_open_cloexec])
           AC_MSG_RESULT([yes])],
          [AC_MSG_RESULT([no])])
@@ -234,7 +234,7 @@
      CFLAGS="$CFLAGS $XINE_CFLAGS"
      LIBS="$LIBS $XINE_LIBS"
      AC_LINK_IFELSE(
-         [AC_LANG_PROGRAM([],[xine_socket_cloexec();])],
+         [AC_LANG_PROGRAM([char xine_socket_cloexec(void);],[xine_socket_cloexec();])],
          [AC_DEFINE([HAVE_XINE_SOCKET_CLOEXEC], [1], [Define if xine-lib supports xine_socket_cloexec])
           AC_MSG_RESULT([yes])],
          [AC_MSG_RESULT([no])])
@@ -250,7 +250,7 @@
      CFLAGS="$CFLAGS $XINE_CFLAGS"
      LIBS="$LIBS $XINE_LIBS"
      AC_LINK_IFELSE(
-         [AC_LANG_PROGRAM([
+         [AC_LANG_PROGRAM([char xine_list_next_value(void);
          ],[
 xine_list_next_value ();
          ])],
--- a/configure.ac
+++ b/configure.ac
@@ -641,7 +641,8 @@ dnl
 dnl Check for clock_gettime() in librt
 dnl
 AC_MSG_CHECKING(whether librt is needed)
-AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <unistd.h>
+AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <time.h>
+                                     #include <unistd.h>
                                      #include <sys/time.h>]],
                                    [[#if _POSIX_TIMERS > 0
                                      struct timespec ts;