[lldb] Remove FileSpec::GetLastPathComponent

As far as I can tell, this just computes the filename of the FileSpec,
which is already conveniently stored in m_filename. We can use
FileSpec::GetFilename() instead.

Differential Revision: https://reviews.llvm.org/D149663

lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp

@@ -623,7 +623,7 @@ size_t ObjectFileELF::GetModuleSpecifications(
             if (!gnu_debuglink_crc) {
               LLDB_SCOPED_TIMERF(
                   "Calculating module crc32 %s with size %" PRIu64 " KiB",
-                  file.GetLastPathComponent().AsCString(),
+                  file.GetFilename().AsCString(),
                   (length - file_offset) / 1024);
 
               // For core files - which usually don't happen to have a