[Rd] fix for a minor build error in R-1.9.0 with XFree86 4.4.0 (PR#6805)

[jbrzusto at ualberta.ca]

Hi, 

In trying to build R 1.9.0, I ran into a problem building the x11()
device support under XFree86 4.4.0:

   make[4]: Entering directory `/home/john/build/R-1.9.0/src/modules/X11'
   gcc -I. -I../../../src/include -I../../../src/include -I/usr/X11R6/include -I/usr/local/include -DHAVE_CONFIG_H  -fPIC  -g -O2 -c dataentry.c -o dataentry.lo
   In file included from dataentry.c:31:
   /usr/X11R6/include/X11/Xlib.h:1389: parse error before "_Xconst"
   /usr/X11R6/include/X11/Xlib.h:1477: parse error before "char"
   /usr/X11R6/include/X11/Xlib.h:1505: parse error before "_Xconst"
   ... many messages omitted

The build is successful and the x11() device works fine if 

R-1.9.0/src/modules/X11/dataentry.c:30 is commented, in order
to re-require function protoypes:

   #include <stdlib.h>
   
   /* don't use X11 function prototypes (which tend to ...): */
   /* #define NeedFunctionPrototypes 0 */
   #include <X11/X.h>
   
Here are my gcc and XFree86 versions:

947$ gcc -v

Reading specs from /usr/lib/gcc-lib/ppc-yellowdog-linux/3.2.2/specs
Configured with: ../configure --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --enable-shared --enable-threads=posix --disable-checking --with-system-zlib --enable-__cxa_atexit --host=ppc-yellowdog-linux
Thread model: posix
gcc version 3.2.2 20030217 (Yellow Dog Linux 3.0 3.2.2-2a)

948$ X -version

XFree86 Version 4.4.0
Release Date: 29 February 2004
X Protocol Version 11, Revision 0, Release 6.6
Build Operating System: Linux 2.6.5 ppc [ELF] 
Current Operating System: Linux bio-c90.biology.ualberta.ca 2.6.5 #4 Tue Apr 20 11:47:27 MDT 2004 ppc
Build Date: 18 April 2004
Changelog Date: 29 February 2004
        Before reporting problems, check http://www.XFree86.Org/
        to make sure that you have the latest version.
Module Loader present

================================================================
Thanks for all your work on this excellent program!

Regards,

John Brzustowski