Avoid "test: too many arguments" error if some $with_ string is empty.

src/configure.in

@@ -58,7 +58,7 @@ dnl ---------------------------------------------------------------------
 dnl             Check for FLTK
 AC_ARG_WITH(fltk, [ --with-fltk=<d>    find FLTK in -I<d>/include/FL -L<d>/lib ], with_fltk=$withval, with_fltk=/usr/local)
 
-if test -n "$with_fltk" -a -d "$with_fltk"; then
+if test -n "$with_fltk" && test -d "$with_fltk"; then
 	# maybe should test both $with_fltk and the include directory therein??
 	if test -f "$with_fltk/include/FL/Fl.H"; then
 	   FLTK_INC=-I$with_fltk/include
@@ -94,7 +94,7 @@ if test "$with_mesa" != "yes"; then
             AC_CHECK_LIB(GLU, gluProject, GLLIBS="-lGLU -lGL",
                          :, -lGL $XLIBS -lm), :, $XLIBS -lm)
 fi
-if test -z "$GLLIBS" -a "$with_mesa" != "no"; then
+if test -z "$GLLIBS" && test "no" != "$with_mesa"; then
         AC_CHECK_LIB(MesaGL, glBegin,
             AC_CHECK_LIB(MesaGLU, gluProject, GLLIBS="-lMesaGLU -lMesaGL",
                          :, -lMesaGL $XLIBS -lm), :, $XLIBS -lm)
@@ -196,7 +196,7 @@ AC_SUBST(CC)
 AC_SUBST(CXX)
 
 starlab_path="$with_kira"
-if test "$with_kira" = "maybe" -o "$with_kira" = "yes"; then
+if test "$with_kira" = "maybe" || test "$with_kira" = "yes"; then
    if test -d "$STARLAB_PATH"; then
       starlab_path="$STARLAB_PATH"
    else
@@ -204,7 +204,7 @@ if test "$with_kira" = "maybe" -o "$with_kira" = "yes"; then
    fi
 fi
 
-if test -n "$starlab_path" -a -d "$starlab_path"; then
+if test -n "$starlab_path" && test -d "$starlab_path"; then
       echo "Configuring with starlab=$starlab_path" 
       KIRA_INC=-I$starlab_path/inc
       KIRA_LIB="-L$starlab_path/lib -ltdyn -ldyn -lnode -lsstar -lstd"
@@ -221,7 +221,7 @@ AC_ARG_WITH(ieeeio-lib, [    --with-ieeeio-lib=LDOPTS  (-LDIR/lib -lieeeio) ],
 AC_ARG_WITH(ieeeio-inc, [    --with-ieeeio-inc=INCOPTS (-IDIR/include)],
 		[IEEEIO_INC="$withval"; with_ieeeio=yes])
 
-if test -n "$with_ieeeio" -a "no" != $with_ieeeio; then
+if test -n "$with_ieeeio" && test "no" != $with_ieeeio; then
     if test "yes" = "$with_ieeeio"; then
 	IEEEIO_LIB=${IEEEIO_LIB:-"-lieeeio"}
     else
@@ -239,7 +239,7 @@ AC_ARG_WITH(elumens-lib, [    --with-elumens-lib=LDOPTS (-LDIR/lib -lspiclops)],
 AC_ARG_WITH(elumens-inc, [    --with-elumens-inc=INCOPTS (-IDIR/include)],
 		[ELUMENS_INC="$withval"; with_elumens=yes])
 
-if test -n "$with_elumens" -a "no" != "$with_elumens"; then
+if test -n "$with_elumens" && test "no" != "$with_elumens"; then
     if test "yes" = "$with_elumens"; then
 	ELUMENS_LIB=${ELUMENS_LIB:-"-lspiclops"}
     else
@@ -254,7 +254,7 @@ dnl ---------------------------------------------------------------------
 dnl             Check for CAVE
 AC_ARG_WITH(cave, [ --with-cave=<d>    find CAVE in -I<d>/include -L<d>/lib ], with_cave=$withval)
 
-if test -n "$with_cave" -a -d "$with_cave"; then
+if test -n "$with_cave" && test -d "$with_cave"; then
 	# maybe should test both $with_cave and the include directory therein??
 	if test -f "$with_cave/include/cave_ogl.h"; then
 	   CAVE_INC=-I$with_cave/include
@@ -278,7 +278,7 @@ PV_FLAGS="$PV_FLAGS -DUSE_NETHACK"
 PV_FLAGS="$PV_FLAGS -DUSE_WARP"
 
 AC_ARG_WITH(model, [  --with-model  Accept Maya obj models], with_model=$withval, with_model=yes)
-if test -n "$with_model" -a "no" != "$with_model"; then
+if test -n "$with_model" && test "no" != "$with_model"; then
     PV_FLAGS="$PV_FLAGS -DUSE_MODEL"
 fi