add --enable-xwayland configure option: USE_XWAYLAND controls XWayland support independently from USE_X11_BACKEND; LINK_X11 conditional links libX11 when either is enabled; X11 libs no longer linked in pure Wayland mode

configure.ac

@@ -748,6 +748,25 @@ AS_IF([test "x$enable_x11_backend" = "xyes"],
     [unsupported="$unsupported X11Backend"])
 AM_CONDITIONAL([USE_X11_BACKEND], [test "x$enable_x11_backend" = "xyes"])
 
+m4_divert_push([INIT_PREPARE])dnl
+AC_ARG_ENABLE([xwayland],
+    [AS_HELP_STRING([--enable-xwayland],
+        [enable XWayland support in the Wayland compositor @<:@default=same as enable-x11-backend@:>@])],
+    [AS_CASE(["$enableval"],
+        [yes|no], [],
+        [AC_MSG_ERROR([bad value $enableval for --enable-xwayland])])],
+    [enable_xwayland=$enable_x11_backend])
+m4_divert_pop([INIT_PREPARE])dnl
+
+AS_IF([test "x$enable_xwayland" = "xyes"],
+    [AC_DEFINE([USE_XWAYLAND], [1],
+        [Define to 1 to enable XWayland support in the Wayland compositor])
+     supported_core="$supported_core XWayland"],
+    [unsupported="$unsupported XWayland"])
+AM_CONDITIONAL([USE_XWAYLAND], [test "x$enable_xwayland" = "xyes"])
+
+AM_CONDITIONAL([LINK_X11], [test "x$enable_x11_backend" = "xyes" -o "x$enable_xwayland" = "xyes"])
+
 
 dnl X11 support inside libwraster (wrlib)
 dnl =====================================

src/Makefile.am

@@ -240,7 +240,7 @@ AM_CPPFLAGS = $(DFLAGS) \
 	-I$(srcdir)/backend/wayland \
 	@HEADER_SEARCH_PATH@
 
-if USE_X11_BACKEND
+if USE_XWAYLAND
 AM_CPPFLAGS += -DUSE_XWAYLAND
 endif
 
@@ -249,14 +249,14 @@ wmaker_LDADD = \
 	$(top_builddir)/WINGs/libWINGs.la\
 	$(top_builddir)/WINGs/libWUtil.la\
 	$(top_builddir)/wrlib/libwraster.la\
-	@XLFLAGS@ \
-	@LIBXRANDR@ \
-	@LIBXINERAMA@ \
-	@XLIBS@ \
 	@WLROOTS_LIBS@ \
 	@LIBM@ \
 	@INTLIBS@
 
+if LINK_X11
+wmaker_LDADD += @XLFLAGS@ @LIBXRANDR@ @LIBXINERAMA@ @XLIBS@
+endif
+
 ######################################################################
 
 # Create a 'silent rule' for our make check the same way automake does