wayland-cursor: add an option that changes the cursor theme directory

Some distros (e.g. gentoo) install cursor themes in non-standard
directories. Add option --with-icondir to configure.sh that sets the
directory in which to look for cursors.

configure.ac

@@ -55,6 +55,11 @@ AC_ARG_ENABLE([documentation],
 
 AM_CONDITIONAL(ENABLE_SCANNER, test "x$enable_scanner" = xyes)
 
+AC_ARG_WITH(icondir, [  --with-icondir=<dir>    Look for cursor icons here],
+		     [  ICONDIR=$withval],
+		     [  ICONDIR=${datadir}/icons])
+AC_SUBST([ICONDIR])
+
 EXPAT_LIB=""
 AC_ARG_WITH(expat, [  --with-expat=<dir>      Use expat from here],
 		   [ expat=$withval

cursor/Makefile.am

@@ -11,4 +11,8 @@ libwayland_cursor_la_LIBADD = $(top_builddir)/src/libwayland-client.la
 pkgconfigdir = $(libdir)/pkgconfig
 pkgconfig_DATA = wayland-cursor.pc
 
-AM_CFLAGS = $(GCC_CFLAGS) -I$(top_builddir)/src -I$(top_srcdir)/src
+AM_CFLAGS = \
+	$(GCC_CFLAGS) \
+	-I$(top_builddir)/src \
+	-I$(top_srcdir)/src \
+	-DICONDIR=\"$(ICONDIR)\"