configure bug on Solaris 2.5.1

[Albert Chin-A-Young <china pprd abbott com>]

On Solaris 2.5.1 and gimp 0.99.21, the set of libraries set when Xmu
is found is incorrect (to link against Xmu, we first link against
SM and ICE to determine if they are necessary but the linker line
never includes -lSM and -lICE on the first pass). The following
patch corrects this. There were simply too many commas in the Xmu
section of configure.in

-- 
albert chin (china@pprd.abbott.com)
*** configure.in.orig	Sun Mar 15 03:14:11 1998
--- configure.in	Wed Mar 18 09:42:12 1998
***************
*** 96,102 ****
        WEBBROWSER="webbrowser"; LIBXMU_LIB='-lXmu -lXt -lSM -lICE',
        AC_CHECK_LIB(Xmu, XmuUpdateMapHints,
  	WEBBROWSER="webbrowser"; LIBXMU_LIB='-lXmu -lXt',
! 	AC_MSG_WARN(*** webbrowser plug-in will not be built ***), -lXt), -lXt, -lSM, -lICE)
    fi
  
  dnl Test for libaa
--- 96,102 ----
        WEBBROWSER="webbrowser"; LIBXMU_LIB='-lXmu -lXt -lSM -lICE',
        AC_CHECK_LIB(Xmu, XmuUpdateMapHints,
  	WEBBROWSER="webbrowser"; LIBXMU_LIB='-lXmu -lXt',
! 	AC_MSG_WARN(*** webbrowser plug-in will not be built ***), -lXt), -lXt -lSM -lICE)
    fi
  
  dnl Test for libaa