Problem Installing GRASS4.1 - XDriver

[duncan_a at wrcplc.co.uk]

From:	NAME: Alistair Duncan
	FUNC: GIS Group <DUNCAN_A at SATURNA1@TITAN>
To:	NAME: GRASSu List <smtp%"grassu-list at moon.cecer.army.mil"@internet>,
	NAME: GRASS Bug <smtp%"grassbug at zorro.cecer.army.mil"@internet>

Hello,

I'm trying to install GRASS v4.1 update 5 on a Sun Sparc 2 running SunOS 4.1.3.

It seems to install fine, apart from the X Drivers - which are vital. The
GISGEN script falls over when trying to compile the X Driver with the following
message :-

-----------------------------------------------------------

GISGEN: src/display/devices/XDRIVER  ..............
..
..
..
cc -O -D_NO_PROTO -I/export/homeb/users/grass/grass4.1/src/include -c
SWITCHER.C
./includes.h: 9: Can't find include file X11/Xos.h
./includes.h: 11: Can't find include file X11/Xlib.h
./includes.h: 12: Can't find include file X11/Xutil.h

***. Error code 2.
make: Fatal error: Command failed for target 'OBJ/SWITCHER.o'
Current working directory
/export/homeb/users/grass/grass4.1/src/display/devices/XDRIVER/XDRIVER

***. Error code 1.
make: Fatal error: Command failed for target 'all'
GISGEN failure at STEP: src/display/devices/XDRIVER



----------------------------------------------------------

Does anybody know how I can solve this problem and get the X drivers working ??
One possibility is that the X11 library files Xos.h, Xlib.h and Xutil.h are
missing - has anyone got a workaround for this, or could they point me to an
ftp site that has these files??


Thanks very much in advance for any help,

Alastair Duncan