Have all VCL plugin related defines in config_vclplug.h

Add the 'ENABLE_GTK3' and 'ENABLE_QT5' there
to allow using sth like

    #include <config_vclplug.h>
    #if ENABLE_GTK3
    // your code here
    #endif

for these as well.

Remove 'config_gtk3_kde5.h{,.in}', 'config_kde5.h{,.in}'
and 'config_qt5.h{,.in}'; they aren't included anywhere.
('QT5_HAVE_GLIB' is only used in Makefiles, so there's no
need to have it in a config header and 'KDE5_HAVE_GLIB' is
not used anywhere at all.)

Change-Id: Iea7906880f57dde782c50f2520e8d9b358f6bc82
Reviewed-on: https://gerrit.libreoffice.org/73204
Tested-by: Jenkins
Reviewed-by: Katarina Behrens <Katarina.Behrens@cib.de>

config_host/config_gtk3_kde5.h.in

-/*
-Settings for GTK3/KDE5 integration.
-*/
-
-#ifndef CONFIG_GTK3_KDE5_H
-#define CONFIG_GTK3_KDE5_H
-
-#define ENABLE_GTK3_KDE5 0
-
-#endif

config_host/config_kde5.h.in

-/*
-Settings for KDE5 integration.
-*/
-
-#ifndef CONFIG_KDE5_H
-#define CONFIG_KDE5_H
-
-#define KDE5_HAVE_GLIB 0
-
-#endif

config_host/config_qt5.h.in

-/*
-Settings for QT5 integration.
-*/
-
-#ifndef CONFIG_QT5_H
-#define CONFIG_QT5_H
-
-#define ENABLE_QT5 0
-#define QT5_HAVE_GLIB 0
-
-#endif

config_host/config_vclplug.h.in

 /*
 
-Settings about which X11 desktops have support enabled.
+Settings about which desktops have support enabled.
 
 */
 
@@ -8,7 +8,9 @@ Settings about which X11 desktops have support enabled.
 #define CONFIG_VCLPLUG_H
 
 #define ENABLE_GTK 0
-#define ENABLE_KDE5 0
+#define ENABLE_GTK3 0
 #define ENABLE_GTK3_KDE5 0
+#define ENABLE_KDE5 0
+#define ENABLE_QT5 0
 
 #endif

configure.ac

@@ -10229,6 +10229,7 @@ if test "x$enable_gtk3" = "xyes"; then
     : ${with_system_cairo:=yes}
     PKG_CHECK_MODULES(GTK3, gtk+-3.0 >= 3.18 gtk+-unix-print-3.0 gmodule-no-export-2.0 glib-2.0 >= 2.38 cairo, ENABLE_GTK3="TRUE", ENABLE_GTK3="")
     if test "x$ENABLE_GTK3" = "xTRUE"; then
+        AC_DEFINE(ENABLE_GTK3)
         R="gtk3"
         dnl Avoid installed by unpackaged files for now.
         if test -z "$PKGFORMAT"; then
@@ -11171,7 +11172,6 @@ the root of your Qt installation by exporting QT5DIR before running "configure".
     PKG_CHECK_MODULES(QT5_GLIB,[glib-2.0 >= 2.4],
         [
             QT5_HAVE_GLIB=1
-            AC_DEFINE(QT5_HAVE_GLIB,1)
         ],
         AC_MSG_WARN([[No Glib found, Qt5 support will not use native file pickers!]])
     )
@@ -12710,9 +12710,6 @@ AC_CONFIG_HEADERS([config_host/config_liblangtag.h])
 AC_CONFIG_HEADERS([config_host/config_libnumbertext.h])
 AC_CONFIG_HEADERS([config_host/config_locales.h])
 AC_CONFIG_HEADERS([config_host/config_mpl.h])
-AC_CONFIG_HEADERS([config_host/config_qt5.h])
-AC_CONFIG_HEADERS([config_host/config_kde5.h])
-AC_CONFIG_HEADERS([config_host/config_gtk3_kde5.h])
 AC_CONFIG_HEADERS([config_host/config_oox.h])
 AC_CONFIG_HEADERS([config_host/config_options.h])
 AC_CONFIG_HEADERS([config_host/config_options_calc.h])