init: allow '.' and '@' in service names

Services implementing HIDL HALs must be named the same as the HIDL
package, e.g. android.hardware.nfc@1.0.  Allow init to accept names
containing '.' and '@'.

Also combined logic for legal property names and legal service names.

Bug: 31458381
Bug: 32109611
Test: Tested creating service nfc@1.0-service which creates property
'init.svc.nfc@1.0-service' with and without this change. This service
successfully started only with this change.

Change-Id: Ie7a4310742bc03498d774d37b3b5fafa7c6068cc
Signed-off-by: Iliyan Malchev <malchev@google.com>
diff --git a/init/property_service.h b/init/property_service.h
index dbaed34..e3a2acb 100644
--- a/init/property_service.h
+++ b/init/property_service.h
@@ -34,6 +34,7 @@
 extern void start_property_service(void);
 std::string property_get(const char* name);
 extern int property_set(const char *name, const char *value);
+extern bool is_legal_property_name(const std::string &name);
 
 
 #endif  /* _INIT_PROPERTY_H */