Clear dlerror before executing anything.

This makes sure that an old error isn't shown when dlopening if it fails
and dlerror isn't set for some reason.

Test: hidl_test
Change-Id: I8468a2c588280488fe9569c58f89c921db119717
diff --git a/transport/ServiceManagement.cpp b/transport/ServiceManagement.cpp
index fec29d1..387b161 100644
--- a/transport/ServiceManagement.cpp
+++ b/transport/ServiceManagement.cpp
@@ -141,6 +141,8 @@
         // TODO: lookup in VINTF instead
         // TODO(b/34135607): Remove HAL_LIBRARY_PATH_SYSTEM
 
+        dlerror(); // clear
+
         for (const std::string &path : {
             HAL_LIBRARY_PATH_ODM, HAL_LIBRARY_PATH_VENDOR, HAL_LIBRARY_PATH_SYSTEM
         }) {