Revert "Stopped Unix plugin loader from throwing #4661"

This reverts commit 1fd5883620.

plugin-unix.diff

@@ -1,15 +0,0 @@
-diff --git a/src/lib/arch/unix/ArchPluginUnix.cpp b/src/lib/arch/unix/ArchPluginUnix.cpp
-index 997c274..3e390f0 100644
---- a/src/lib/arch/unix/ArchPluginUnix.cpp
-+++ b/src/lib/arch/unix/ArchPluginUnix.cpp
-@@ -76,8 +76,8 @@ ArchPluginUnix::load()
- 		void* library = dlopen(path.c_str(), RTLD_LAZY);
- 
- 		if (library == NULL) {
--			LOG((CLOG_ERR "failed to load plugin: %s", (*it).c_str()));
--			throw XArch(dlerror());
-+			LOG((CLOG_ERR "failed to load plugin '%s', error: %s", (*it).c_str(), dlerror()));
-+			continue;
- 		}
- 
- 		String filename = synergy::string::removeFileExt(*it);