Ignore verbose parser generator output file more generally

Depending on from where bison is called, the file might not end up in
the same directory as the .y file, but the location of the Makefile.
This has been seen on FreeBSD.

src/libstrongswan/.gitignore

@@ -1,2 +1,5 @@
 oid.[ch]
 proposal_keywords_static.[ch]
+settings/settings_lexer.c
+settings/settings_parser.[ch]
+settings_parser.output

src/libstrongswan/settings/.gitignore

@@ -1,3 +0,0 @@
-settings_lexer.c
-settings_parser.[ch]
-settings_parser.output

src/starter/.gitignore

@@ -2,4 +2,4 @@ starter
 keywords.[ch]
 parser/lexer.c
 parser/parser.[ch]
-parser/parser.output
+parser.output