Get Bison to build again when configured with --enable-gcc-warnings.

* src/location.c, src/location.h, src/main.c, src/scan-code.l: Add some
missing #include's.
* src/scan-code.l (handle_action_dollar, handle_action_at): Rename
loc argument as it shadows a global.
* src/scan-gram.l: Remove stray comma that prevents boundary_set
invocation.

* src/.cvsignore: Add scan-code.c.

src/.cvsignore

@@ -6,6 +6,7 @@ Makefile
 Makefile.in
 bison
 revision.c
+scan-code.c
 scan-gram.c
 scan-skel.c
 yacc