Implicit const char* cast removed, operator<< added to hidl_string.

hidl_string no longer will provide an implicit cast to const char* as it
interfers with other expected behaviors of the class.  It now emulated
std::string in requiring a call to .c_str() to get the same behavior.

Bug:  36532780
Test:  Build the tree for marlin, bullhead, bat
Change-Id: I6ba76522ef65aa211bc156144990ad8b7495b051
diff --git a/transport/ServiceManagement.cpp b/transport/ServiceManagement.cpp
index 5ba3ec3..23349c3 100644
--- a/transport/ServiceManagement.cpp
+++ b/transport/ServiceManagement.cpp
@@ -196,7 +196,7 @@
                     continue;
                 }
 
-                IBase *interface = (*generator)(name);
+                IBase *interface = (*generator)(name.c_str());
 
                 if (interface == nullptr) {
                     dlclose(handle);