ANDROID: fix redefinition error for restricted vendor hooks

Because of the multi-inclusion oddities of tracepoints, the
multi-inclusion protection in vendor_hooks.h caused issues
if more than 1 vendor hook header file with restricted vendor
hooks defined were included with "CREATE_TRACE_POINTS"
defined (redefinition of symbol errors).

The problem is fixed by removing the multiple-inclusion
protection as is done for regular tracepoints.

Fixes: 5965ee663d66 ("ANDROID: add support for vendor hooks")
Bug: 163076069
Signed-off-by: Todd Kjos <tkjos@google.com>
Change-Id: Ic177db1693a6a2db58f08917e9115c7e6c2971b6

include/trace/hooks/vendor_hooks.h

@@ -1,7 +1,11 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 
-#if !defined(_TRACE_VENDOR_HOOKS_H) || defined(TRACE_HEADER_MULTI_READ)
-#define _TRACE_VENDOR_HOOKS_H
+/*
+ * Note: we intentionally omit include file ifdef protection
+ *  This is due to the way trace events work. If a file includes two
+ *  trace event headers under one "CREATE_TRACE_POINTS" the first include
+ *  will override the DECLARE_RESTRICTED_HOOK and break the second include.
+ */
 
 #include <linux/tracepoint.h>
 
@@ -13,6 +17,7 @@
 #define DECLARE_RESTRICTED_HOOK(name, proto, args, cond) \
 	DEFINE_TRACE(name)
 
+
 /* prevent additional recursion */
 #undef TRACE_HEADER_MULTI_READ
 #else /* TRACE_HEADER_MULTI_READ */
@@ -61,6 +66,7 @@
 	}								\
 	/* vendor hooks cannot be unregistered */			\
 
+#undef DECLARE_RESTRICTED_HOOK
 #define DECLARE_RESTRICTED_HOOK(name, proto, args, cond)		\
 	__DECLARE_HOOK(name, PARAMS(proto), PARAMS(args),		\
 			cond,						\
@@ -68,5 +74,3 @@
 			PARAMS(__data, args))
 
 #endif /* TRACE_HEADER_MULTI_READ */
-
-#endif /* _TRACE_VENDOR_HOOKS_H */