configure: set HAVE_foo_PLATFORM as applicable

Rather than having multiple places that define the macros, do it just
once in configure. Makes existing code a bit shorter and easier to
manage as we fix the VL targets with follow-up commits.

Cc: mesa-stable@lists.freedesktop.org
Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
Reviewed-by: Eric Engestrom <eric@engestrom.ch>
diff --git a/configure.ac b/configure.ac
index f741efc..5652112 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1684,22 +1684,27 @@
 		if test "x$WAYLAND_SCANNER" = "x:"; then
 			AC_MSG_ERROR([wayland-scanner is needed to compile the wayland platform])
 		fi
+		DEFINES="$DEFINES -DHAVE_WAYLAND_PLATFORM"
 		;;
 
 	x11)
 		PKG_CHECK_MODULES([XCB_DRI2], [x11-xcb xcb xcb-dri2 >= $XCBDRI2_REQUIRED xcb-xfixes])
+		DEFINES="$DEFINES -DHAVE_X11_PLATFORM"
 		;;
 
 	drm)
 		test "x$enable_gbm" = "xno" &&
 			AC_MSG_ERROR([EGL platform drm needs gbm])
+		DEFINES="$DEFINES -DHAVE_DRM_PLATFORM"
 		;;
 
 	surfaceless)
+		DEFINES="$DEFINES -DHAVE_SURFACELESS_PLATFORM"
 		;;
 
 	android)
 		PKG_CHECK_MODULES([ANDROID], [cutils hardware sync])
+		DEFINES="$DEFINES -DHAVE_ANDROID_PLATFORM"
 		;;
 
 	*)