Add missing lambda return types.

Author: Allen-Webb

src/Common/Utility.hpp

@@ -189,7 +189,7 @@ namespace usbguard
     std::function<std::string(const std::string&, const struct dirent*)> filter,
     std::function<int(const std::string&, const std::string&)> loader,
     std::function<bool(const std::pair<std::string, std::string>&, const std::pair<std::string, std::string>&)> sorter = \
-      [](const std::pair<std::string, std::string>& a, const std::pair<std::string, std::string>& b)
+      [](const std::pair<std::string, std::string>& a, const std::pair<std::string, std::string>& b) -> bool
   {
     return a.first < b.first;
   },

src/Library/UMockdevDeviceManager.cpp

@@ -289,7 +289,7 @@ namespace usbguard
     _umockdev_deviceroot = std::string(envval);
     _testbed.reset(umockdev_testbed_new());
     USBGUARD_LOG(Info) << "umockdev device directory set to " << _umockdev_deviceroot;
-    const auto lambdaUMockdevFilterEntry = [](const std::string& fullpath, const struct dirent* dirent) {
+    const auto lambdaUMockdevFilterEntry = [](const std::string& fullpath, const struct dirent* dirent) -> std::string {
       (void)dirent;
       struct stat st = {};
 
@@ -305,7 +305,7 @@ namespace usbguard
         return std::string();
       }
     };
-    const auto lambdaUMockdevAddFromFile = [this](const std::string& fullpath, const std::string& loadpath) {
+    const auto lambdaUMockdevAddFromFile = [this](const std::string& fullpath, const std::string& loadpath) -> int {
       (void)fullpath;
 
       for (const auto& device_path : umockdevLoadFromFile(loadpath)) {