Let lock_guard deduce its template argument

No functional change, this is a cleanup.

With C++17, it's no longer necessary to specify the teplate argument
when it can be deduced from the types of constructor arguments. This
allows de-cluttering our locking statements.

To avoid typos, this patch was mechanically generated:

  perl -p -i -e 's/std::lock_guard<std::mutex>/std::lock_guard/g' \
    $(find . -name '*.cpp' -o -name '*.h')

Change-Id: Ibb15d9a6c5b1c861d81353e47d25474eb1d4c2df
diff --git a/server/RouteController.cpp b/server/RouteController.cpp
index 16947af..6774fd5 100644
--- a/server/RouteController.cpp
+++ b/server/RouteController.cpp
@@ -155,7 +155,7 @@
 }
 
 uint32_t RouteController::getIfIndex(const char* interface) {
-    std::lock_guard<std::mutex> lock(sInterfaceToTableLock);
+    std::lock_guard lock(sInterfaceToTableLock);
 
     auto iter = sInterfaceToTable.find(interface);
     if (iter == sInterfaceToTable.end()) {
@@ -167,7 +167,7 @@
 }
 
 uint32_t RouteController::getRouteTableForInterface(const char* interface) {
-    std::lock_guard<std::mutex> lock(sInterfaceToTableLock);
+    std::lock_guard lock(sInterfaceToTableLock);
     return getRouteTableForInterfaceLocked(interface);
 }
 
@@ -191,7 +191,7 @@
     addTableName(ROUTE_TABLE_LEGACY_NETWORK, ROUTE_TABLE_NAME_LEGACY_NETWORK, &contents);
     addTableName(ROUTE_TABLE_LEGACY_SYSTEM,  ROUTE_TABLE_NAME_LEGACY_SYSTEM,  &contents);
 
-    std::lock_guard<std::mutex> lock(sInterfaceToTableLock);
+    std::lock_guard lock(sInterfaceToTableLock);
     for (const auto& entry : sInterfaceToTable) {
         addTableName(entry.second, entry.first, &contents);
     }
@@ -927,7 +927,7 @@
 
 // Returns 0 on success or negative errno on failure.
 WARN_UNUSED_RESULT int RouteController::flushRoutes(const char* interface) {
-    std::lock_guard<std::mutex> lock(sInterfaceToTableLock);
+    std::lock_guard lock(sInterfaceToTableLock);
 
     uint32_t table = getRouteTableForInterfaceLocked(interface);
     if (table == RT_TABLE_UNSPEC) {