Fixed "broken OpenGL setup" configure check, which used to report
false errors on some systems.

configure

diff --git a/configure b/configure
index 063def7..c56c879 100755
--- a/configure
+++ b/configure
@@ -8156,15 +8156,6 @@
 
         if test "x$with_opengl" != "xno"
     then
-        if test -f /usr/X11R6/lib/libGL.a -a ! -f /usr/X11R6/lib/libGL.so -a ! -f /usr/X11R6/lib/libGL.dylib
-        then
-	    { { echo "$as_me:$LINENO: error: /usr/X11R6/lib/libGL.a is present on your system.
-This prevents linking to OpenGL. Delete the file and restart configure." >&5
-echo "$as_me: error: /usr/X11R6/lib/libGL.a is present on your system.
-This prevents linking to OpenGL. Delete the file and restart configure." >&2;}
-   { (exit 1); exit 1; }; }
-        fi
-
 
 
 for ac_header in GL/gl.h GL/glx.h
@@ -8511,7 +8502,17 @@
 #define HAVE_OPENGL 1
 _ACEOF
 
+		else
+                    if test -f /usr/X11R6/lib/libGL.a
+                    then
+                       { { echo "$as_me:$LINENO: error: /usr/X11R6/lib/libGL.a is present on your system.
+This prevents linking to OpenGL. Delete the file and restart configure." >&5
+echo "$as_me: error: /usr/X11R6/lib/libGL.a is present on your system.
+This prevents linking to OpenGL. Delete the file and restart configure." >&2;}
+   { (exit 1); exit 1; }; }
+                    fi
 		fi
+
 	        		echo "$as_me:$LINENO: checking for gluLookAt in -lGLU" >&5
 echo $ECHO_N "checking for gluLookAt in -lGLU... $ECHO_C" >&6
 if test "${ac_cv_lib_GLU_gluLookAt+set}" = set; then

configure.ac

diff --git a/configure.ac b/configure.ac
index 77d5025..ef253c6 100644
--- a/configure.ac
+++ b/configure.ac
@@ -356,12 +356,6 @@
     dnl Check for the presence of OpenGL
     if test "x$with_opengl" != "xno"
     then
-        if test -f /usr/X11R6/lib/libGL.a -a ! -f /usr/X11R6/lib/libGL.so -a ! -f /usr/X11R6/lib/libGL.dylib
-        then 
-	    AC_MSG_ERROR([/usr/X11R6/lib/libGL.a is present on your system.
-This prevents linking to OpenGL. Delete the file and restart configure.])
-        fi
-
 	AC_CHECK_HEADERS(GL/gl.h GL/glx.h)
 	if test "$ac_cv_header_GL_gl_h" = "yes" -a "$ac_cv_header_GL_glx_h" = "yes"
 	then
@@ -388,7 +382,14 @@
 		then
 			OPENGLFILES='$(OPENGLFILES)'
 			AC_DEFINE(HAVE_OPENGL, 1, [Define if OpenGL is present on the system])
+		else
+                    if test -f /usr/X11R6/lib/libGL.a
+                    then 
+                       AC_MSG_ERROR([/usr/X11R6/lib/libGL.a is present on your system.
+This prevents linking to OpenGL. Delete the file and restart configure.])
+                    fi
 		fi
+
 	        dnl Check for GLU32 library.
 		AC_CHECK_LIB(GLU,gluLookAt,
 			     [OPENGL_LIBS="$OPENGL_LIBS -lGLU"