Remove unnecessary calls to expand path

When using the Meterpreter Binaries gem to locate the path to the
meterpreter DLLs, it's not necessary to use File.expand_path on
the result because the gem's code does this already.

This commit simple removes those unnecessary calls.

lib/rex/post/meterpreter/client_core.rb

@@ -159,15 +159,13 @@ class ClientCore < Extension
     path = MeterpreterBinaries.path(modname, client.binary_suffix)
 
     if opts['ExtensionPath']
-      path = opts['ExtensionPath']
+      path = ::File.expand_path(opts['ExtensionPath'])
     end
 
     if path.nil?
       raise RuntimeError, "No module of the name #{modname}.#{client.binary_suffix} found", caller
     end
 
-    path = ::File.expand_path(path)
-
     # Load the extension DLL
     commands = load_library(
         'LibraryFilePath' => path,

lib/rex/post/meterpreter/extensions/priv/priv.rb

@@ -50,8 +50,6 @@ class Priv < Extension
       raise RuntimeError, "elevator.#{binary_suffix} not found", caller
     end
 
-    elevator_path = ::File.expand_path( elevator_path )
-
     elevator_data = ""
 
     ::File.open( elevator_path, "rb" ) { |f|

lib/rex/post/meterpreter/extensions/stdapi/ui.rb

@@ -154,37 +154,43 @@ class UI < Rex::Post::UI
   def screenshot( quality=50 )
     request = Packet.create_request( 'stdapi_ui_desktop_screenshot' )
     request.add_tlv( TLV_TYPE_DESKTOP_SCREENSHOT_QUALITY, quality )
+
     # include the x64 screenshot dll if the host OS is x64
     if( client.sys.config.sysinfo['Architecture'] =~ /^\S*x64\S*/ )
       screenshot_path = MeterpreterBinaries.path('screenshot','x64.dll')
       if screenshot_path.nil?
         raise RuntimeError, "screenshot.x64.dll not found", caller
       end
-      screenshot_path = ::File.expand_path( screenshot_path )
+
       screenshot_dll  = ''
       ::File.open( screenshot_path, 'rb' ) do |f|
         screenshot_dll += f.read( f.stat.size )
       end
+
       request.add_tlv( TLV_TYPE_DESKTOP_SCREENSHOT_PE64DLL_BUFFER, screenshot_dll, false, true )
       request.add_tlv( TLV_TYPE_DESKTOP_SCREENSHOT_PE64DLL_LENGTH, screenshot_dll.length )
     end
+
     # but always include the x86 screenshot dll as we can use it for wow64 processes if we are on x64
     screenshot_path = MeterpreterBinaries.path('screenshot','x86.dll')
     if screenshot_path.nil?
       raise RuntimeError, "screenshot.x86.dll not found", caller
     end
-    screenshot_path = ::File.expand_path( screenshot_path )
+
     screenshot_dll  = ''
     ::File.open( screenshot_path, 'rb' ) do |f|
       screenshot_dll += f.read( f.stat.size )
     end
+
     request.add_tlv( TLV_TYPE_DESKTOP_SCREENSHOT_PE32DLL_BUFFER, screenshot_dll, false, true )
     request.add_tlv( TLV_TYPE_DESKTOP_SCREENSHOT_PE32DLL_LENGTH, screenshot_dll.length )
+
     # send the request and return the jpeg image if successfull.
     response = client.send_request( request )
     if( response.result == 0 )
       return response.get_tlv_value( TLV_TYPE_DESKTOP_SCREENSHOT )
     end
+
     return nil
   end