meson: fix asn1Parser command call

meson.build

@@ -124,10 +124,10 @@ tasn1 = dependency('libtasn1')
 thread = dependency('threads')
 
 spnego_asn1_target = custom_target('spnego_asn1.c',
-  output: 'spnego_asn1.c',
   input: 'contrib/spnego/spnego.asn1',
-  command: ['asn1Parser', '-o', '@INPUT@', '-n', 'spnego_asn1_conf',
-            '@OUTPUT@'])
+  output: 'spnego_asn1.c',
+  command: ['asn1Parser', '-o', '@OUTPUT@', '-n', 'spnego_asn1_conf',
+            '@INPUT@'])
 
 libdsm_sources = [
   'contrib/mdx/md4.c',