libsoup: Honor gssapi option

gssapi was enabled by default after the meson migration leading to
be enabled it accidentally.  Properly pass corresponding MESON_ARGS based on
`gssapi' option.  While here also update a CONFIGURE_ARGS usage to the
corresponding MESON_ARGS one.

Index: Makefile
===================================================================
RCS file: /cvsroot/pkgsrc/net/libsoup/Makefile,v
retrieving revision 1.52
diff -u -p -r1.52 Makefile
--- Makefile	16 Aug 2019 13:08:58 -0000	1.52
+++ Makefile	17 Aug 2019 14:29:40 -0000
@@ -37,7 +37,7 @@ BUILDLINK_API_DEPENDS.glib2+=	glib2>=2.3
 BUILDLINK_API_DEPENDS.gobject-introspection+=	gobject-introspection>=0.9.5
 BUILDLINK_DEPMETHOD.gobject-introspection=	build
 .include "../../devel/gobject-introspection/buildlink3.mk"
-CONFIGURE_ARGS+=	--enable-introspection
+MESON_ARGS+=	-Dintrospection=true
 .include "../../textproc/libxml2/buildlink3.mk"
 .include "../../www/libpsl/buildlink3.mk"
 .include "../../devel/py-meson/build.mk"
Index: options.mk
===================================================================
RCS file: /cvsroot/pkgsrc/net/libsoup/options.mk,v
retrieving revision 1.5
diff -u -p -r1.5 options.mk
--- options.mk	16 Aug 2019 13:08:58 -0000	1.5
+++ options.mk	17 Aug 2019 14:29:40 -0000
@@ -7,5 +7,8 @@ PKG_SUGGESTED_OPTIONS=
 .include "../../mk/bsd.options.mk"
 
 .if !empty(PKG_OPTIONS:Mgssapi)
+MESON_ARGS+=	-Dgssapi=false
 .  include "../../mk/krb5.buildlink3.mk"
+.else
+MESON_ARGS+=	-Dgssapi=true
 .endif