MAINT-5232: Abbreviate __FILE__ path in log_subsystem_cleanup().

LLError::abbreviateFile() is specifically to avoid cluttering log output with
the prefix of an absolute file path on the original build system, pointless
for anyone trying to read the log.

indra/llcommon/llcleanup.cpp

@@ -18,11 +18,12 @@
 // external library headers
 // other Linden headers
 #include "llerror.h"
+#include "llerrorcontrol.h"
 
 void log_subsystem_cleanup(const char* file, int line, const char* function,
                            const char* classname)
 {
-    LL_INFOS("Cleanup") << file << "(" << line << "): calling " 
-                        << classname << "::cleanupClass() in "
+    LL_INFOS("Cleanup") << LLError::abbreviateFile(file) << "(" << line << "): "
+                        << "calling " << classname << "::cleanupClass() in "
                         << function << LL_ENDL;
 }