cocci rules: remove <id>'s from rules that don't need them

The <id> in the <rulename> part of the coccinelle syntax[1] is for our
purposes there to declares if we have inter-dependencies between
different rules.

But such <id>'s must be unique within a given semantic patch file.  As
we'll be processing a concatenated version of our rules in the
subsequent commit let's remove these names. They weren't being used
for the semantic patches themselves, and equated to a short comment
about the rule.

Both the filename and context of the rules makes it clear what they're
doing, so we're not gaining anything from keeping these. Retaining
them goes against recommendations that "contrib/coccinelle/README"
will be making in the subsequent commit.

This leaves only one named rule in our sources, where it's needed for
a "<id> <-> <extends> <id>" relationship:

	$ git -P grep '^@ ' -- contrib/coccinelle/
	contrib/coccinelle/swap.cocci:@ swap @
	contrib/coccinelle/swap.cocci:@ extends swap @

1. https://coccinelle.gitlabpages.inria.fr/website/docs/main_grammar.html

Signed-off-by: Ævar Arnfjörð Bjarmason <[email protected]>
Signed-off-by: Taylor Blau <[email protected]>

Author: avar

contrib/coccinelle/hashmap.cocci

@@ -1,4 +1,4 @@
-@ hashmap_entry_init_usage @
+@@
 expression E;
 struct hashmap_entry HME;
 @@

contrib/coccinelle/preincr.cocci

@@ -1,4 +1,4 @@
-@ preincrement @
+@@
 identifier i;
 @@
 - ++i > 1

contrib/coccinelle/strbuf.cocci

@@ -1,4 +1,4 @@
-@ strbuf_addf_with_format_only @
+@@
 expression E;
 constant fmt !~ "%";
 @@

contrib/coccinelle/swap.cocci

@@ -1,4 +1,4 @@
-@ swap_with_declaration @
+@@
 type T;
 identifier tmp;
 T a, b;