Fix detection of multibuf.h by the configure script
Without this patch, configure prints:
checking X11/extensions/multibuf.h usability... no
configure: WARNING: X11/extensions/multibuf.h: present but cannot be compiled
checking X11/extensions/multibuf.h presence... yes
configure: WARNING: X11/extensions/multibuf.h: check for missing prerequisite headers?
configure: WARNING: X11/extensions/multibuf.h: see the Autoconf documentation
configure: WARNING: X11/extensions/multibuf.h: section "Present But Cannot Be Compiled"
configure: WARNING: X11/extensions/multibuf.h: proceeding with the compiler's result
checking for X11/extensions/multibuf.h... no
Based on a patch by Dan HorĂ¡k.
Gbp-Pq: Name multibuf.patch
AC_CHECK_HEADERS(iomanip.h limits.h values.h float.h)
AC_CHECK_HEADERS(siginfo.h bits/sigset.h bstring.h sys/types.h sys/select.h)
AC_CHECK_HEADERS(X11/extensions/transovl.h X11/extensions/readdisplay.h)
-AC_CHECK_HEADERS(X11/extensions/multibuf.h)
-AC_CHECK_HEADERS(sys/filio.h sys/mman.h libc.h)
-AC_CHECK_HEADERS(X11/extensions/multibuf.h)
+AC_CHECK_HEADERS([X11/Xlib.h X11/extensions/multibuf.h], [], [], [#include <X11/Xlib.h>])
AC_CHECK_HEADERS(sys/filio.h sys/mman.h libc.h)
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